Build Node.js P2P Zoom Clone Video Chat Using simple-peer & WebRTC Library in Javascript

What we are going to look at through this article is Build Node.js P2P Zoom Clone Video Chat Using simple-peer & WebRTC Library in Javascript We will look at this in detail through this article.

Build Node.js P2P Zoom Clone Video Chat Using simple-peer & WebRTC Library in Javascript

Build Node.js P2P Zoom Clone Video Chat Using simple-peer & WebRTC Library in Javascript

const express = require('express')
const app = express()
const http = require('http').Server(app)
const io = require('socket.io')(http)
const port = process.env.PORT || 3000

app.use(express.static(__dirname + "/public"))
let clients = 0

io.on('connection', function (socket) {
    socket.on("NewClient", function () {
        if (clients < 2) {
            if (clients == 1) {
                this.emit('CreatePeer')
            }
        }
        else
            this.emit('SessionActive')
        clients++;
    })
    socket.on('Offer', SendOffer)
    socket.on('Answer', SendAnswer)
    socket.on('disconnect', Disconnect)
})

function Disconnect() {
    if (clients > 0) {
        if (clients <= 2)
            this.broadcast.emit("Disconnect")
        clients--
    }
}

function SendOffer(offer) {
    this.broadcast.emit("BackOffer", offer)
}

function SendAnswer(data) {
    this.broadcast.emit("BackAnswer", data)
}

http.listen(port, () => console.log(`Active on ${port} port`))
<html>

<head>
    <title>Video Chat App</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
    <link href="main.css" rel="stylesheet">
</head>

<body>
    <div class="container-fluid">
        <div class="row h-10 w-100">
            <div class="col">
                <select id="filter" class="w-100 bg-dark text-light ml-2 mt-2 select font-weight-bold border">
                    <option value="none">Normal</option>
                    <option value="grayscale(100%)">B & W</option>
                    <option value="sepia(100%)">Old School</option>
                    <option value="contrast(150%)">Lumination</option>
                    <option value="blur(20px)">Hidden Mist</option>
                    <option value="invert(100%)">Dracula</option>
                    <option value="hue-rotate(180deg">X-men Beast</option>
                    <option value="saturate(25)">Super Saiyan God</option>
                </select>
            </div>
            <div class="col">
                <div class="float-right mt-3">
                    <input class="form-check-input" type="checkbox" id="theme">
                    <label class="form-check-label" for="theme">
                        Dark Theme
                    </label>
                </div>
            </div>
        </div>
        <div class="row h-90 w-100">
            <div class="col-12 col-sm-6 d-flex justify-content-center">
                <div class="embed-responsive embed-responsive-16by9">
                    <video class="embed-responsive-item" muted></video>
                </div>
            </div>
            <div class="col-12 col-sm-6 d-flex justify-content-center">
                <div id="peerDiv" class="embed-responsive embed-responsive-16by9">
                </div>
            </div>
        </div>
    </div>

    <script src="/socket.io/socket.io.js"></script>
    <script src="bundle.js"></script>
</body>

</html>
video {
    transform: rotateY(180deg); 
}

.select {
    height: 30px;
}

.h-90 {
    height: 90% !important;
}

.h-10 {
    height: 10% !important;
}

#peerVideo:hover {
    opacity: 0.6;
    cursor: pointer;
}

.centered {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}
let Peer = require('simple-peer')
let socket = io()
const video = document.querySelector('video')
const filter = document.querySelector('#filter')
const checkboxTheme = document.querySelector('#theme')
let client = {}
let currentFilter
//get stream
navigator.mediaDevices.getUserMedia({ video: true, audio: true })
    .then(stream => {
        socket.emit('NewClient')
        video.srcObject = stream
        video.play()

        filter.addEventListener('change', (event) => {
            currentFilter = event.target.value
            video.style.filter = currentFilter
            SendFilter(currentFilter)
            event.preventDefault
        })

        //used to initialize a peer
        function InitPeer(type) {
            let peer = new Peer({ initiator: (type == 'init') ? true : false, stream: stream, trickle: false })
            peer.on('stream', function (stream) {
                CreateVideo(stream)
            })
            //This isn't working in chrome; works perfectly in firefox.
            // peer.on('close', function () {
            //     document.getElementById("peerVideo").remove();
            //     peer.destroy()
            // })
            peer.on('data', function (data) {
                let decodedData = new TextDecoder('utf-8').decode(data)
                let peervideo = document.querySelector('#peerVideo')
                peervideo.style.filter = decodedData
            })
            return peer
        }

        //for peer of type init
        function MakePeer() {
            client.gotAnswer = false
            let peer = InitPeer('init')
            peer.on('signal', function (data) {
                if (!client.gotAnswer) {
                    socket.emit('Offer', data)
                }
            })
            client.peer = peer
        }

        //for peer of type not init
        function FrontAnswer(offer) {
            let peer = InitPeer('notInit')
            peer.on('signal', (data) => {
                socket.emit('Answer', data)
            })
            peer.signal(offer)
            client.peer = peer
        }

        function SignalAnswer(answer) {
            client.gotAnswer = true
            let peer = client.peer
            peer.signal(answer)
        }

        function CreateVideo(stream) {
            CreateDiv()

            let video = document.createElement('video')
            video.id = 'peerVideo'
            video.srcObject = stream
            video.setAttribute('class', 'embed-responsive-item')
            document.querySelector('#peerDiv').appendChild(video)
            video.play()
            //wait for 1 sec
            setTimeout(() => SendFilter(currentFilter), 1000)

            video.addEventListener('click', () => {
                if (video.volume != 0)
                    video.volume = 0
                else
                    video.volume = 1
            })

        }

        function SessionActive() {
            document.write('Session Active. Please come back later')
        }

        function SendFilter(filter) {
            if (client.peer) {
                client.peer.send(filter)
            }
        }

        function RemovePeer() {
            document.getElementById("peerVideo").remove();
            document.getElementById("muteText").remove();
            if (client.peer) {
                client.peer.destroy()
            }
        }

        socket.on('BackOffer', FrontAnswer)
        socket.on('BackAnswer', SignalAnswer)
        socket.on('SessionActive', SessionActive)
        socket.on('CreatePeer', MakePeer)
        socket.on('Disconnect', RemovePeer)

    })
    .catch(err => document.write(err))

checkboxTheme.addEventListener('click', () => {
    if (checkboxTheme.checked == true) {
        document.body.style.backgroundColor="#212529"
        if (document.querySelector('#muteText')) {
            document.querySelector('#muteText').style.color = "#fff"
        }

    }
    else {
        document.body.style.backgroundColor="#fff"
        if (document.querySelector('#muteText')) {
            document.querySelector('#muteText').style.color = "#212529"
        }
    }
}
)

function CreateDiv() {
    let div = document.createElement('div')
    div.setAttribute('class', "centered")
    div.id = "muteText"
    div.innerHTML = "Click to Mute/Unmute"
    document.querySelector('#peerDiv').appendChild(div)
    if (checkboxTheme.checked == true)
        document.querySelector('#muteText').style.color = "#fff"
}
(function(){function r(e,n,t){function o(i,f){if(!n[i]){if(!e[i]){var c="function"==typeof require&&require;if(!f&&c)return c(i,!0);if(u)return u(i,!0);var a=new Error("Cannot find module '"+i+"'");throw a.code="MODULE_NOT_FOUND",a}var p=n[i]={exports:{}};e[i][0].call(p.exports,function(r){var n=e[i][1][r];return o(n||r)},p,p.exports,r,e,n,t)}return n[i].exports}for(var u="function"==typeof require&&require,i=0;i<t.length;i++)o(t[i]);return o}return r})()({1:[function(require,module,exports){
'use strict'

exports.byteLength = byteLength
exports.toByteArray = toByteArray
exports.fromByteArray = fromByteArray

var lookup = []
var revLookup = []
var Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array

var code="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
for (var i = 0, len = code.length; i < len; ++i) {
  lookup[i] = code[i]
  revLookup[code.charCodeAt(i)] = i
}

// Support decoding URL-safe base64 strings, as Node.js does.
// See: https://en.wikipedia.org/wiki/Base64#URL_applications
revLookup['-'.charCodeAt(0)] = 62
revLookup['_'.charCodeAt(0)] = 63

function getLens (b64) {
  var len = b64.length

  if (len % 4 > 0) {
    throw new Error('Invalid string. Length must be a multiple of 4')
  }

  // Trim off extra bytes after placeholder bytes are found
  // See: https://github.com/beatgammit/base64-js/issues/42
  var validLen = b64.indexOf('=')
  if (validLen === -1) validLen = len

  var placeHoldersLen = validLen === len
    ? 0
    : 4 - (validLen % 4)

  return [validLen, placeHoldersLen]
}

// base64 is 4/3 + up to two characters of the original data
function byteLength (b64) {
  var lens = getLens(b64)
  var validLen = lens[0]
  var placeHoldersLen = lens[1]
  return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
}

function _byteLength (b64, validLen, placeHoldersLen) {
  return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
}

function toByteArray (b64) {
  var tmp
  var lens = getLens(b64)
  var validLen = lens[0]
  var placeHoldersLen = lens[1]

  var arr = new Arr(_byteLength(b64, validLen, placeHoldersLen))

  var curByte = 0

  // if there are placeholders, only get up to the last complete 4 chars
  var len = placeHoldersLen > 0
    ? validLen - 4
    : validLen

  for (var i = 0; i < len; i += 4) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 18) |
      (revLookup[b64.charCodeAt(i + 1)] << 12) |
      (revLookup[b64.charCodeAt(i + 2)] << 6) |
      revLookup[b64.charCodeAt(i + 3)]
    arr[curByte++] = (tmp >> 16) & 0xFF
    arr[curByte++] = (tmp >> 8) & 0xFF
    arr[curByte++] = tmp & 0xFF
  }

  if (placeHoldersLen === 2) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 2) |
      (revLookup[b64.charCodeAt(i + 1)] >> 4)
    arr[curByte++] = tmp & 0xFF
  }

  if (placeHoldersLen === 1) {
    tmp =
      (revLookup[b64.charCodeAt(i)] << 10) |
      (revLookup[b64.charCodeAt(i + 1)] << 4) |
      (revLookup[b64.charCodeAt(i + 2)] >> 2)
    arr[curByte++] = (tmp >> 8) & 0xFF
    arr[curByte++] = tmp & 0xFF
  }

  return arr
}

function tripletToBase64 (num) {
  return lookup[num >> 18 & 0x3F] +
    lookup[num >> 12 & 0x3F] +
    lookup[num >> 6 & 0x3F] +
    lookup[num & 0x3F]
}

function encodeChunk (uint8, start, end) {
  var tmp
  var output = []
  for (var i = start; i < end; i += 3) {
    tmp =
      ((uint8[i] << 16) & 0xFF0000) +
      ((uint8[i + 1] << 8) & 0xFF00) +
      (uint8[i + 2] & 0xFF)
    output.push(tripletToBase64(tmp))
  }
  return output.join('')
}

function fromByteArray (uint8) {
  var tmp
  var len = uint8.length
  var extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
  var parts = []
  var maxChunkLength = 16383 // must be multiple of 3

  // go through the array every three bytes, we'll deal with trailing stuff later
  for (var i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
    parts.push(encodeChunk(
      uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)
    ))
  }

  // pad the end with zeros, but make sure to not forget the extra bytes
  if (extraBytes === 1) {
    tmp = uint8[len - 1]
    parts.push(
      lookup[tmp >> 2] +
      lookup[(tmp << 4) & 0x3F] +
      '=='
    )
  } else if (extraBytes === 2) {
    tmp = (uint8[len - 2] << 8) + uint8[len - 1]
    parts.push(
      lookup[tmp >> 10] +
      lookup[(tmp >> 4) & 0x3F] +
      lookup[(tmp << 2) & 0x3F] +
      '='
    )
  }

  return parts.join('')
}

},{}],2:[function(require,module,exports){

},{}],3:[function(require,module,exports){
(function (Buffer){
/*!
 * The buffer module from node.js, for the browser.
 *
 * @author   Feross Aboukhadijeh <https://feross.org>
 * @license  MIT
 */
/* eslint-disable no-proto */

'use strict'

var base64 = require('base64-js')
var ieee754 = require('ieee754')

exports.Buffer = Buffer
exports.SlowBuffer = SlowBuffer
exports.INSPECT_MAX_BYTES = 50

var K_MAX_LENGTH = 0x7fffffff
exports.kMaxLength = K_MAX_LENGTH

/**
 * If `Buffer.TYPED_ARRAY_SUPPORT`:
 *   === true    Use Uint8Array implementation (fastest)
 *   === false   Print warning and recommend using `buffer` v4.x which has an Object
 *               implementation (most compatible, even IE6)
 *
 * Browsers that support typed arrays are IE 10+, Firefox 4+, Chrome 7+, Safari 5.1+,
 * Opera 11.6+, iOS 4.2+.
 *
 * We report that the browser does not support typed arrays if the are not subclassable
 * using __proto__. Firefox 4-29 lacks support for adding new properties to `Uint8Array`
 * (See: https://bugzilla.mozilla.org/show_bug.cgi?id=695438). IE 10 lacks support
 * for __proto__ and has a buggy typed array implementation.
 */
Buffer.TYPED_ARRAY_SUPPORT = typedArraySupport()

if (!Buffer.TYPED_ARRAY_SUPPORT && typeof console !== 'undefined' &&
    typeof console.error === 'function') {
  console.error(
    'This browser lacks typed array (Uint8Array) support which is required by ' +
    '`buffer` v5.x. Use `buffer` v4.x if you require old browser support.'
  )
}

function typedArraySupport () {
  // Can typed array instances can be augmented?
  try {
    var arr = new Uint8Array(1)
    arr.__proto__ = { __proto__: Uint8Array.prototype, foo: function () { return 42 } }
    return arr.foo() === 42
  } catch (e) {
    return false
  }
}

Object.defineProperty(Buffer.prototype, 'parent', {
  enumerable: true,
  get: function () {
    if (!Buffer.isBuffer(this)) return undefined
    return this.buffer
  }
})

Object.defineProperty(Buffer.prototype, 'offset', {
  enumerable: true,
  get: function () {
    if (!Buffer.isBuffer(this)) return undefined
    return this.byteOffset
  }
})

function createBuffer (length) {
  if (length > K_MAX_LENGTH) {
    throw new RangeError('The value "' + length + '" is invalid for option "size"')
  }
  // Return an augmented `Uint8Array` instance
  var buf = new Uint8Array(length)
  buf.__proto__ = Buffer.prototype
  return buf
}

/**
 * The Buffer constructor returns instances of `Uint8Array` that have their
 * prototype changed to `Buffer.prototype`. Furthermore, `Buffer` is a subclass of
 * `Uint8Array`, so the returned instances will have all the node `Buffer` methods
 * and the `Uint8Array` methods. Square bracket notation works as expected -- it
 * returns a single octet.
 *
 * The `Uint8Array` prototype remains unmodified.
 */

function Buffer (arg, encodingOrOffset, length) {
  // Common case.
  if (typeof arg === 'number') {
    if (typeof encodingOrOffset === 'string') {
      throw new TypeError(
        'The "string" argument must be of type string. Received type number'
      )
    }
    return allocUnsafe(arg)
  }
  return from(arg, encodingOrOffset, length)
}

// Fix subarray() in ES2016. See: https://github.com/feross/buffer/pull/97
if (typeof Symbol !== 'undefined' && Symbol.species != null &&
    Buffer[Symbol.species] === Buffer) {
  Object.defineProperty(Buffer, Symbol.species, {
    value: null,
    configurable: true,
    enumerable: false,
    writable: false
  })
}

Buffer.poolSize = 8192 // not used by this implementation

function from (value, encodingOrOffset, length) {
  if (typeof value === 'string') {
    return fromString(value, encodingOrOffset)
  }

  if (ArrayBuffer.isView(value)) {
    return fromArrayLike(value)
  }

  if (value == null) {
    throw TypeError(
      'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
      'or Array-like Object. Received type ' + (typeof value)
    )
  }

  if (isInstance(value, ArrayBuffer) ||
      (value && isInstance(value.buffer, ArrayBuffer))) {
    return fromArrayBuffer(value, encodingOrOffset, length)
  }

  if (typeof value === 'number') {
    throw new TypeError(
      'The "value" argument must not be of type number. Received type number'
    )
  }

  var valueOf = value.valueOf && value.valueOf()
  if (valueOf != null && valueOf !== value) {
    return Buffer.from(valueOf, encodingOrOffset, length)
  }

  var b = fromObject(value)
  if (b) return b

  if (typeof Symbol !== 'undefined' && Symbol.toPrimitive != null &&
      typeof value[Symbol.toPrimitive] === 'function') {
    return Buffer.from(
      value[Symbol.toPrimitive]('string'), encodingOrOffset, length
    )
  }

  throw new TypeError(
    'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
    'or Array-like Object. Received type ' + (typeof value)
  )
}

/**
 * Functionally equivalent to Buffer(arg, encoding) but throws a TypeError
 * if value is a number.
 * Buffer.from(str[, encoding])
 * Buffer.from(array)
 * Buffer.from(buffer)
 * Buffer.from(arrayBuffer[, byteOffset[, length]])
 **/
Buffer.from = function (value, encodingOrOffset, length) {
  return from(value, encodingOrOffset, length)
}

// Note: Change prototype *after* Buffer.from is defined to workaround Chrome bug:
// https://github.com/feross/buffer/pull/148
Buffer.prototype.__proto__ = Uint8Array.prototype
Buffer.__proto__ = Uint8Array

function assertSize (size) {
  if (typeof size !== 'number') {
    throw new TypeError('"size" argument must be of type number')
  } else if (size < 0) {
    throw new RangeError('The value "' + size + '" is invalid for option "size"')
  }
}

function alloc (size, fill, encoding) {
  assertSize(size)
  if (size <= 0) {
    return createBuffer(size)
  }
  if (fill !== undefined) {
    // Only pay attention to encoding if it's a string. This
    // prevents accidentally sending in a number that would
    // be interpretted as a start offset.
    return typeof encoding === 'string'
      ? createBuffer(size).fill(fill, encoding)
      : createBuffer(size).fill(fill)
  }
  return createBuffer(size)
}

/**
 * Creates a new filled Buffer instance.
 * alloc(size[, fill[, encoding]])
 **/
Buffer.alloc = function (size, fill, encoding) {
  return alloc(size, fill, encoding)
}

function allocUnsafe (size) {
  assertSize(size)
  return createBuffer(size < 0 ? 0 : checked(size) | 0)
}

/**
 * Equivalent to Buffer(num), by default creates a non-zero-filled Buffer instance.
 * */
Buffer.allocUnsafe = function (size) {
  return allocUnsafe(size)
}
/**
 * Equivalent to SlowBuffer(num), by default creates a non-zero-filled Buffer instance.
 */
Buffer.allocUnsafeSlow = function (size) {
  return allocUnsafe(size)
}

function fromString (string, encoding) {
  if (typeof encoding !== 'string' || encoding === '') {
    encoding = 'utf8'
  }

  if (!Buffer.isEncoding(encoding)) {
    throw new TypeError('Unknown encoding: ' + encoding)
  }

  var length = byteLength(string, encoding) | 0
  var buf = createBuffer(length)

  var actual = buf.write(string, encoding)

  if (actual !== length) {
    // Writing a hex string, for example, that contains invalid characters will
    // cause everything after the first invalid character to be ignored. (e.g.
    // 'abxxcd' will be treated as 'ab')
    buf = buf.slice(0, actual)
  }

  return buf
}

function fromArrayLike (array) {
  var length = array.length < 0 ? 0 : checked(array.length) | 0
  var buf = createBuffer(length)
  for (var i = 0; i < length; i += 1) {
    buf[i] = array[i] & 255
  }
  return buf
}

function fromArrayBuffer (array, byteOffset, length) {
  if (byteOffset < 0 || array.byteLength < byteOffset) {
    throw new RangeError('"offset" is outside of buffer bounds')
  }

  if (array.byteLength < byteOffset + (length || 0)) {
    throw new RangeError('"length" is outside of buffer bounds')
  }

  var buf
  if (byteOffset === undefined && length === undefined) {
    buf = new Uint8Array(array)
  } else if (length === undefined) {
    buf = new Uint8Array(array, byteOffset)
  } else {
    buf = new Uint8Array(array, byteOffset, length)
  }

  // Return an augmented `Uint8Array` instance
  buf.__proto__ = Buffer.prototype
  return buf
}

function fromObject (obj) {
  if (Buffer.isBuffer(obj)) {
    var len = checked(obj.length) | 0
    var buf = createBuffer(len)

    if (buf.length === 0) {
      return buf
    }

    obj.copy(buf, 0, 0, len)
    return buf
  }

  if (obj.length !== undefined) {
    if (typeof obj.length !== 'number' || numberIsNaN(obj.length)) {
      return createBuffer(0)
    }
    return fromArrayLike(obj)
  }

  if (obj.type === 'Buffer' && Array.isArray(obj.data)) {
    return fromArrayLike(obj.data)
  }
}

function checked (length) {
  // Note: cannot use `length < K_MAX_LENGTH` here because that fails when
  // length is NaN (which is otherwise coerced to zero.)
  if (length >= K_MAX_LENGTH) {
    throw new RangeError('Attempt to allocate Buffer larger than maximum ' +
                         'size: 0x' + K_MAX_LENGTH.toString(16) + ' bytes')
  }
  return length | 0
}

function SlowBuffer (length) {
  if (+length != length) { // eslint-disable-line eqeqeq
    length = 0
  }
  return Buffer.alloc(+length)
}

Buffer.isBuffer = function isBuffer (b) {
  return b != null && b._isBuffer === true &&
    b !== Buffer.prototype // so Buffer.isBuffer(Buffer.prototype) will be false
}

Buffer.compare = function compare (a, b) {
  if (isInstance(a, Uint8Array)) a = Buffer.from(a, a.offset, a.byteLength)
  if (isInstance(b, Uint8Array)) b = Buffer.from(b, b.offset, b.byteLength)
  if (!Buffer.isBuffer(a) || !Buffer.isBuffer(b)) {
    throw new TypeError(
      'The "buf1", "buf2" arguments must be one of type Buffer or Uint8Array'
    )
  }

  if (a === b) return 0

  var x = a.length
  var y = b.length

  for (var i = 0, len = Math.min(x, y); i < len; ++i) {
    if (a[i] !== b[i]) {
      x = a[i]
      y = b[i]
      break
    }
  }

  if (x < y) return -1
  if (y < x) return 1
  return 0
}

Buffer.isEncoding = function isEncoding (encoding) {
  switch (String(encoding).toLowerCase()) {
    case 'hex':
    case 'utf8':
    case 'utf-8':
    case 'ascii':
    case 'latin1':
    case 'binary':
    case 'base64':
    case 'ucs2':
    case 'ucs-2':
    case 'utf16le':
    case 'utf-16le':
      return true
    default:
      return false
  }
}

Buffer.concat = function concat (list, length) {
  if (!Array.isArray(list)) {
    throw new TypeError('"list" argument must be an Array of Buffers')
  }

  if (list.length === 0) {
    return Buffer.alloc(0)
  }

  var i
  if (length === undefined) {
    length = 0
    for (i = 0; i < list.length; ++i) {
      length += list[i].length
    }
  }

  var buffer = Buffer.allocUnsafe(length)
  var pos = 0
  for (i = 0; i < list.length; ++i) {
    var buf = list[i]
    if (isInstance(buf, Uint8Array)) {
      buf = Buffer.from(buf)
    }
    if (!Buffer.isBuffer(buf)) {
      throw new TypeError('"list" argument must be an Array of Buffers')
    }
    buf.copy(buffer, pos)
    pos += buf.length
  }
  return buffer
}

function byteLength (string, encoding) {
  if (Buffer.isBuffer(string)) {
    return string.length
  }
  if (ArrayBuffer.isView(string) || isInstance(string, ArrayBuffer)) {
    return string.byteLength
  }
  if (typeof string !== 'string') {
    throw new TypeError(
      'The "string" argument must be one of type string, Buffer, or ArrayBuffer. ' +
      'Received type ' + typeof string
    )
  }

  var len = string.length
  var mustMatch = (arguments.length > 2 && arguments[2] === true)
  if (!mustMatch && len === 0) return 0

  // Use a for loop to avoid recursion
  var loweredCase = false
  for (;;) {
    switch (encoding) {
      case 'ascii':
      case 'latin1':
      case 'binary':
        return len
      case 'utf8':
      case 'utf-8':
        return utf8ToBytes(string).length
      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return len * 2
      case 'hex':
        return len >>> 1
      case 'base64':
        return base64ToBytes(string).length
      default:
        if (loweredCase) {
          return mustMatch ? -1 : utf8ToBytes(string).length // assume utf8
        }
        encoding = ('' + encoding).toLowerCase()
        loweredCase = true
    }
  }
}
Buffer.byteLength = byteLength

function slowToString (encoding, start, end) {
  var loweredCase = false

  // No need to verify that "this.length <= MAX_UINT32" since it's a read-only
  // property of a typed array.

  // This behaves neither like String nor Uint8Array in that we set start/end
  // to their upper/lower bounds if the value passed is out of range.
  // undefined is handled specially as per ECMA-262 6th Edition,
  // Section 13.3.3.7 Runtime Semantics: KeyedBindingInitialization.
  if (start === undefined || start < 0) {
    start = 0
  }
  // Return early if start > this.length. Done here to prevent potential uint32
  // coercion fail below.
  if (start > this.length) {
    return ''
  }

  if (end === undefined || end > this.length) {
    end = this.length
  }

  if (end <= 0) {
    return ''
  }

  // Force coersion to uint32. This will also coerce falsey/NaN values to 0.
  end >>>= 0
  start >>>= 0

  if (end <= start) {
    return ''
  }

  if (!encoding) encoding = 'utf8'

  while (true) {
    switch (encoding) {
      case 'hex':
        return hexSlice(this, start, end)

      case 'utf8':
      case 'utf-8':
        return utf8Slice(this, start, end)

      case 'ascii':
        return asciiSlice(this, start, end)

      case 'latin1':
      case 'binary':
        return latin1Slice(this, start, end)

      case 'base64':
        return base64Slice(this, start, end)

      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return utf16leSlice(this, start, end)

      default:
        if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
        encoding = (encoding + '').toLowerCase()
        loweredCase = true
    }
  }
}

// This property is used by `Buffer.isBuffer` (and the `is-buffer` npm package)
// to detect a Buffer instance. It's not possible to use `instanceof Buffer`
// reliably in a browserify context because there could be multiple different
// copies of the 'buffer' package in use. This method works even for Buffer
// instances that were created from another copy of the `buffer` package.
// See: https://github.com/feross/buffer/issues/154
Buffer.prototype._isBuffer = true

function swap (b, n, m) {
  var i = b[n]
  b[n] = b[m]
  b[m] = i
}

Buffer.prototype.swap16 = function swap16 () {
  var len = this.length
  if (len % 2 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 16-bits')
  }
  for (var i = 0; i < len; i += 2) {
    swap(this, i, i + 1)
  }
  return this
}

Buffer.prototype.swap32 = function swap32 () {
  var len = this.length
  if (len % 4 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 32-bits')
  }
  for (var i = 0; i < len; i += 4) {
    swap(this, i, i + 3)
    swap(this, i + 1, i + 2)
  }
  return this
}

Buffer.prototype.swap64 = function swap64 () {
  var len = this.length
  if (len % 8 !== 0) {
    throw new RangeError('Buffer size must be a multiple of 64-bits')
  }
  for (var i = 0; i < len; i += 8) {
    swap(this, i, i + 7)
    swap(this, i + 1, i + 6)
    swap(this, i + 2, i + 5)
    swap(this, i + 3, i + 4)
  }
  return this
}

Buffer.prototype.toString = function toString () {
  var length = this.length
  if (length === 0) return ''
  if (arguments.length === 0) return utf8Slice(this, 0, length)
  return slowToString.apply(this, arguments)
}

Buffer.prototype.toLocaleString = Buffer.prototype.toString

Buffer.prototype.equals = function equals (b) {
  if (!Buffer.isBuffer(b)) throw new TypeError('Argument must be a Buffer')
  if (this === b) return true
  return Buffer.compare(this, b) === 0
}

Buffer.prototype.inspect = function inspect () {
  var str=""
  var max = exports.INSPECT_MAX_BYTES
  str = this.toString('hex', 0, max).replace(/(.{2})/g, '$1 ').trim()
  if (this.length > max) str += ' ... '
  return '<Buffer ' + str + '>'
}

Buffer.prototype.compare = function compare (target, start, end, thisStart, thisEnd) {
  if (isInstance(target, Uint8Array)) {
    target = Buffer.from(target, target.offset, target.byteLength)
  }
  if (!Buffer.isBuffer(target)) {
    throw new TypeError(
      'The "target" argument must be one of type Buffer or Uint8Array. ' +
      'Received type ' + (typeof target)
    )
  }

  if (start === undefined) {
    start = 0
  }
  if (end === undefined) {
    end = target ? target.length : 0
  }
  if (thisStart === undefined) {
    thisStart = 0
  }
  if (thisEnd === undefined) {
    thisEnd = this.length
  }

  if (start < 0 || end > target.length || thisStart < 0 || thisEnd > this.length) {
    throw new RangeError('out of range index')
  }

  if (thisStart >= thisEnd && start >= end) {
    return 0
  }
  if (thisStart >= thisEnd) {
    return -1
  }
  if (start >= end) {
    return 1
  }

  start >>>= 0
  end >>>= 0
  thisStart >>>= 0
  thisEnd >>>= 0

  if (this === target) return 0

  var x = thisEnd - thisStart
  var y = end - start
  var len = Math.min(x, y)

  var thisCopy = this.slice(thisStart, thisEnd)
  var targetCopy = target.slice(start, end)

  for (var i = 0; i < len; ++i) {
    if (thisCopy[i] !== targetCopy[i]) {
      x = thisCopy[i]
      y = targetCopy[i]
      break
    }
  }

  if (x < y) return -1
  if (y < x) return 1
  return 0
}

// Finds either the first index of `val` in `buffer` at offset >= `byteOffset`,
// OR the last index of `val` in `buffer` at offset <= `byteOffset`.
//
// Arguments:
// - buffer - a Buffer to search
// - val - a string, Buffer, or number
// - byteOffset - an index into `buffer`; will be clamped to an int32
// - encoding - an optional encoding, relevant is val is a string
// - dir - true for indexOf, false for lastIndexOf
function bidirectionalIndexOf (buffer, val, byteOffset, encoding, dir) {
  // Empty buffer means no match
  if (buffer.length === 0) return -1

  // Normalize byteOffset
  if (typeof byteOffset === 'string') {
    encoding = byteOffset
    byteOffset = 0
  } else if (byteOffset > 0x7fffffff) {
    byteOffset = 0x7fffffff
  } else if (byteOffset < -0x80000000) {
    byteOffset = -0x80000000
  }
  byteOffset = +byteOffset // Coerce to Number.
  if (numberIsNaN(byteOffset)) {
    // byteOffset: it it's undefined, null, NaN, "foo", etc, search whole buffer
    byteOffset = dir ? 0 : (buffer.length - 1)
  }

  // Normalize byteOffset: negative offsets start from the end of the buffer
  if (byteOffset < 0) byteOffset = buffer.length + byteOffset
  if (byteOffset >= buffer.length) {
    if (dir) return -1
    else byteOffset = buffer.length - 1
  } else if (byteOffset < 0) {
    if (dir) byteOffset = 0
    else return -1
  }

  // Normalize val
  if (typeof val === 'string') {
    val = Buffer.from(val, encoding)
  }

  // Finally, search either indexOf (if dir is true) or lastIndexOf
  if (Buffer.isBuffer(val)) {
    // Special case: looking for empty string/buffer always fails
    if (val.length === 0) {
      return -1
    }
    return arrayIndexOf(buffer, val, byteOffset, encoding, dir)
  } else if (typeof val === 'number') {
    val = val & 0xFF // Search for a byte value [0-255]
    if (typeof Uint8Array.prototype.indexOf === 'function') {
      if (dir) {
        return Uint8Array.prototype.indexOf.call(buffer, val, byteOffset)
      } else {
        return Uint8Array.prototype.lastIndexOf.call(buffer, val, byteOffset)
      }
    }
    return arrayIndexOf(buffer, [ val ], byteOffset, encoding, dir)
  }

  throw new TypeError('val must be string, number or Buffer')
}

function arrayIndexOf (arr, val, byteOffset, encoding, dir) {
  var indexSize = 1
  var arrLength = arr.length
  var valLength = val.length

  if (encoding !== undefined) {
    encoding = String(encoding).toLowerCase()
    if (encoding === 'ucs2' || encoding === 'ucs-2' ||
        encoding === 'utf16le' || encoding === 'utf-16le') {
      if (arr.length < 2 || val.length < 2) {
        return -1
      }
      indexSize = 2
      arrLength /= 2
      valLength /= 2
      byteOffset /= 2
    }
  }

  function read (buf, i) {
    if (indexSize === 1) {
      return buf[i]
    } else {
      return buf.readUInt16BE(i * indexSize)
    }
  }

  var i
  if (dir) {
    var foundIndex = -1
    for (i = byteOffset; i < arrLength; i++) {
      if (read(arr, i) === read(val, foundIndex === -1 ? 0 : i - foundIndex)) {
        if (foundIndex === -1) foundIndex = i
        if (i - foundIndex + 1 === valLength) return foundIndex * indexSize
      } else {
        if (foundIndex !== -1) i -= i - foundIndex
        foundIndex = -1
      }
    }
  } else {
    if (byteOffset + valLength > arrLength) byteOffset = arrLength - valLength
    for (i = byteOffset; i >= 0; i--) {
      var found = true
      for (var j = 0; j < valLength; j++) {
        if (read(arr, i + j) !== read(val, j)) {
          found = false
          break
        }
      }
      if (found) return i
    }
  }

  return -1
}

Buffer.prototype.includes = function includes (val, byteOffset, encoding) {
  return this.indexOf(val, byteOffset, encoding) !== -1
}

Buffer.prototype.indexOf = function indexOf (val, byteOffset, encoding) {
  return bidirectionalIndexOf(this, val, byteOffset, encoding, true)
}

Buffer.prototype.lastIndexOf = function lastIndexOf (val, byteOffset, encoding) {
  return bidirectionalIndexOf(this, val, byteOffset, encoding, false)
}

function hexWrite (buf, string, offset, length) {
  offset = Number(offset) || 0
  var remaining = buf.length - offset
  if (!length) {
    length = remaining
  } else {
    length = Number(length)
    if (length > remaining) {
      length = remaining
    }
  }

  var strLen = string.length

  if (length > strLen / 2) {
    length = strLen / 2
  }
  for (var i = 0; i < length; ++i) {
    var parsed = parseInt(string.substr(i * 2, 2), 16)
    if (numberIsNaN(parsed)) return i
    buf[offset + i] = parsed
  }
  return i
}

function utf8Write (buf, string, offset, length) {
  return blitBuffer(utf8ToBytes(string, buf.length - offset), buf, offset, length)
}

function asciiWrite (buf, string, offset, length) {
  return blitBuffer(asciiToBytes(string), buf, offset, length)
}

function latin1Write (buf, string, offset, length) {
  return asciiWrite(buf, string, offset, length)
}

function base64Write (buf, string, offset, length) {
  return blitBuffer(base64ToBytes(string), buf, offset, length)
}

function ucs2Write (buf, string, offset, length) {
  return blitBuffer(utf16leToBytes(string, buf.length - offset), buf, offset, length)
}

Buffer.prototype.write = function write (string, offset, length, encoding) {
  // Buffer#write(string)
  if (offset === undefined) {
    encoding = 'utf8'
    length = this.length
    offset = 0
  // Buffer#write(string, encoding)
  } else if (length === undefined && typeof offset === 'string') {
    encoding = offset
    length = this.length
    offset = 0
  // Buffer#write(string, offset[, length][, encoding])
  } else if (isFinite(offset)) {
    offset = offset >>> 0
    if (isFinite(length)) {
      length = length >>> 0
      if (encoding === undefined) encoding = 'utf8'
    } else {
      encoding = length
      length = undefined
    }
  } else {
    throw new Error(
      'Buffer.write(string, encoding, offset[, length]) is no longer supported'
    )
  }

  var remaining = this.length - offset
  if (length === undefined || length > remaining) length = remaining

  if ((string.length > 0 && (length < 0 || offset < 0)) || offset > this.length) {
    throw new RangeError('Attempt to write outside buffer bounds')
  }

  if (!encoding) encoding = 'utf8'

  var loweredCase = false
  for (;;) {
    switch (encoding) {
      case 'hex':
        return hexWrite(this, string, offset, length)

      case 'utf8':
      case 'utf-8':
        return utf8Write(this, string, offset, length)

      case 'ascii':
        return asciiWrite(this, string, offset, length)

      case 'latin1':
      case 'binary':
        return latin1Write(this, string, offset, length)

      case 'base64':
        // Warning: maxLength not taken into account in base64Write
        return base64Write(this, string, offset, length)

      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return ucs2Write(this, string, offset, length)

      default:
        if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
        encoding = ('' + encoding).toLowerCase()
        loweredCase = true
    }
  }
}

Buffer.prototype.toJSON = function toJSON () {
  return {
    type: 'Buffer',
    data: Array.prototype.slice.call(this._arr || this, 0)
  }
}

function base64Slice (buf, start, end) {
  if (start === 0 && end === buf.length) {
    return base64.fromByteArray(buf)
  } else {
    return base64.fromByteArray(buf.slice(start, end))
  }
}

function utf8Slice (buf, start, end) {
  end = Math.min(buf.length, end)
  var res = []

  var i = start
  while (i < end) {
    var firstByte = buf[i]
    var codePoint = null
    var bytesPerSequence = (firstByte > 0xEF) ? 4
      : (firstByte > 0xDF) ? 3
        : (firstByte > 0xBF) ? 2
          : 1

    if (i + bytesPerSequence <= end) {
      var secondByte, thirdByte, fourthByte, tempCodePoint

      switch (bytesPerSequence) {
        case 1:
          if (firstByte < 0x80) {
            codePoint = firstByte
          }
          break
        case 2:
          secondByte = buf[i + 1]
          if ((secondByte & 0xC0) === 0x80) {
            tempCodePoint = (firstByte & 0x1F) << 0x6 | (secondByte & 0x3F)
            if (tempCodePoint > 0x7F) {
              codePoint = tempCodePoint
            }
          }
          break
        case 3:
          secondByte = buf[i + 1]
          thirdByte = buf[i + 2]
          if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80) {
            tempCodePoint = (firstByte & 0xF) << 0xC | (secondByte & 0x3F) << 0x6 | (thirdByte & 0x3F)
            if (tempCodePoint > 0x7FF && (tempCodePoint < 0xD800 || tempCodePoint > 0xDFFF)) {
              codePoint = tempCodePoint
            }
          }
          break
        case 4:
          secondByte = buf[i + 1]
          thirdByte = buf[i + 2]
          fourthByte = buf[i + 3]
          if ((secondByte & 0xC0) === 0x80 && (thirdByte & 0xC0) === 0x80 && (fourthByte & 0xC0) === 0x80) {
            tempCodePoint = (firstByte & 0xF) << 0x12 | (secondByte & 0x3F) << 0xC | (thirdByte & 0x3F) << 0x6 | (fourthByte & 0x3F)
            if (tempCodePoint > 0xFFFF && tempCodePoint < 0x110000) {
              codePoint = tempCodePoint
            }
          }
      }
    }

    if (codePoint === null) {
      // we did not generate a valid codePoint so insert a
      // replacement char (U+FFFD) and advance only 1 byte
      codePoint = 0xFFFD
      bytesPerSequence = 1
    } else if (codePoint > 0xFFFF) {
      // encode to utf16 (surrogate pair dance)
      codePoint -= 0x10000
      res.push(codePoint >>> 10 & 0x3FF | 0xD800)
      codePoint = 0xDC00 | codePoint & 0x3FF
    }

    res.push(codePoint)
    i += bytesPerSequence
  }

  return decodeCodePointsArray(res)
}

// Based on http://stackoverflow.com/a/22747272/680742, the browser with
// the lowest limit is Chrome, with 0x10000 args.
// We go 1 magnitude less, for safety
var MAX_ARGUMENTS_LENGTH = 0x1000

function decodeCodePointsArray (codePoints) {
  var len = codePoints.length
  if (len <= MAX_ARGUMENTS_LENGTH) {
    return String.fromCharCode.apply(String, codePoints) // avoid extra slice()
  }

  // Decode in chunks to avoid "call stack size exceeded".
  var res=""
  var i = 0
  while (i < len) {
    res += String.fromCharCode.apply(
      String,
      codePoints.slice(i, i += MAX_ARGUMENTS_LENGTH)
    )
  }
  return res
}

function asciiSlice (buf, start, end) {
  var ret=""
  end = Math.min(buf.length, end)

  for (var i = start; i < end; ++i) {
    ret += String.fromCharCode(buf[i] & 0x7F)
  }
  return ret
}

function latin1Slice (buf, start, end) {
  var ret=""
  end = Math.min(buf.length, end)

  for (var i = start; i < end; ++i) {
    ret += String.fromCharCode(buf[i])
  }
  return ret
}

function hexSlice (buf, start, end) {
  var len = buf.length

  if (!start || start < 0) start = 0
  if (!end || end < 0 || end > len) end = len

  var out=""
  for (var i = start; i < end; ++i) {
    out += toHex(buf[i])
  }
  return out
}

function utf16leSlice (buf, start, end) {
  var bytes = buf.slice(start, end)
  var res=""
  for (var i = 0; i < bytes.length; i += 2) {
    res += String.fromCharCode(bytes[i] + (bytes[i + 1] * 256))
  }
  return res
}

Buffer.prototype.slice = function slice (start, end) {
  var len = this.length
  start = ~~start
  end = end === undefined ? len : ~~end

  if (start < 0) {
    start += len
    if (start < 0) start = 0
  } else if (start > len) {
    start = len
  }

  if (end < 0) {
    end += len
    if (end < 0) end = 0
  } else if (end > len) {
    end = len
  }

  if (end < start) end = start

  var newBuf = this.subarray(start, end)
  // Return an augmented `Uint8Array` instance
  newBuf.__proto__ = Buffer.prototype
  return newBuf
}

/*
 * Need to make sure that buffer isn't trying to write out of bounds.
 */
function checkOffset (offset, ext, length) {
  if ((offset % 1) !== 0 || offset < 0) throw new RangeError('offset is not uint')
  if (offset + ext > length) throw new RangeError('Trying to access beyond buffer length')
}

Buffer.prototype.readUIntLE = function readUIntLE (offset, byteLength, noAssert) {
  offset = offset >>> 0
  byteLength = byteLength >>> 0
  if (!noAssert) checkOffset(offset, byteLength, this.length)

  var val = this[offset]
  var mul = 1
  var i = 0
  while (++i < byteLength && (mul *= 0x100)) {
    val += this[offset + i] * mul
  }

  return val
}

Buffer.prototype.readUIntBE = function readUIntBE (offset, byteLength, noAssert) {
  offset = offset >>> 0
  byteLength = byteLength >>> 0
  if (!noAssert) {
    checkOffset(offset, byteLength, this.length)
  }

  var val = this[offset + --byteLength]
  var mul = 1
  while (byteLength > 0 && (mul *= 0x100)) {
    val += this[offset + --byteLength] * mul
  }

  return val
}

Buffer.prototype.readUInt8 = function readUInt8 (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 1, this.length)
  return this[offset]
}

Buffer.prototype.readUInt16LE = function readUInt16LE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 2, this.length)
  return this[offset] | (this[offset + 1] << 8)
}

Buffer.prototype.readUInt16BE = function readUInt16BE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 2, this.length)
  return (this[offset] << 8) | this[offset + 1]
}

Buffer.prototype.readUInt32LE = function readUInt32LE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 4, this.length)

  return ((this[offset]) |
      (this[offset + 1] << 8) |
      (this[offset + 2] << 16)) +
      (this[offset + 3] * 0x1000000)
}

Buffer.prototype.readUInt32BE = function readUInt32BE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 4, this.length)

  return (this[offset] * 0x1000000) +
    ((this[offset + 1] << 16) |
    (this[offset + 2] << 8) |
    this[offset + 3])
}

Buffer.prototype.readIntLE = function readIntLE (offset, byteLength, noAssert) {
  offset = offset >>> 0
  byteLength = byteLength >>> 0
  if (!noAssert) checkOffset(offset, byteLength, this.length)

  var val = this[offset]
  var mul = 1
  var i = 0
  while (++i < byteLength && (mul *= 0x100)) {
    val += this[offset + i] * mul
  }
  mul *= 0x80

  if (val >= mul) val -= Math.pow(2, 8 * byteLength)

  return val
}

Buffer.prototype.readIntBE = function readIntBE (offset, byteLength, noAssert) {
  offset = offset >>> 0
  byteLength = byteLength >>> 0
  if (!noAssert) checkOffset(offset, byteLength, this.length)

  var i = byteLength
  var mul = 1
  var val = this[offset + --i]
  while (i > 0 && (mul *= 0x100)) {
    val += this[offset + --i] * mul
  }
  mul *= 0x80

  if (val >= mul) val -= Math.pow(2, 8 * byteLength)

  return val
}

Buffer.prototype.readInt8 = function readInt8 (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 1, this.length)
  if (!(this[offset] & 0x80)) return (this[offset])
  return ((0xff - this[offset] + 1) * -1)
}

Buffer.prototype.readInt16LE = function readInt16LE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 2, this.length)
  var val = this[offset] | (this[offset + 1] << 8)
  return (val & 0x8000) ? val | 0xFFFF0000 : val
}

Buffer.prototype.readInt16BE = function readInt16BE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 2, this.length)
  var val = this[offset + 1] | (this[offset] << 8)
  return (val & 0x8000) ? val | 0xFFFF0000 : val
}

Buffer.prototype.readInt32LE = function readInt32LE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 4, this.length)

  return (this[offset]) |
    (this[offset + 1] << 8) |
    (this[offset + 2] << 16) |
    (this[offset + 3] << 24)
}

Buffer.prototype.readInt32BE = function readInt32BE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 4, this.length)

  return (this[offset] << 24) |
    (this[offset + 1] << 16) |
    (this[offset + 2] << 8) |
    (this[offset + 3])
}

Buffer.prototype.readFloatLE = function readFloatLE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 4, this.length)
  return ieee754.read(this, offset, true, 23, 4)
}

Buffer.prototype.readFloatBE = function readFloatBE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 4, this.length)
  return ieee754.read(this, offset, false, 23, 4)
}

Buffer.prototype.readDoubleLE = function readDoubleLE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 8, this.length)
  return ieee754.read(this, offset, true, 52, 8)
}

Buffer.prototype.readDoubleBE = function readDoubleBE (offset, noAssert) {
  offset = offset >>> 0
  if (!noAssert) checkOffset(offset, 8, this.length)
  return ieee754.read(this, offset, false, 52, 8)
}

function checkInt (buf, value, offset, ext, max, min) {
  if (!Buffer.isBuffer(buf)) throw new TypeError('"buffer" argument must be a Buffer instance')
  if (value > max || value < min) throw new RangeError('"value" argument is out of bounds')
  if (offset + ext > buf.length) throw new RangeError('Index out of range')
}

Buffer.prototype.writeUIntLE = function writeUIntLE (value, offset, byteLength, noAssert) {
  value = +value
  offset = offset >>> 0
  byteLength = byteLength >>> 0
  if (!noAssert) {
    var maxBytes = Math.pow(2, 8 * byteLength) - 1
    checkInt(this, value, offset, byteLength, maxBytes, 0)
  }

  var mul = 1
  var i = 0
  this[offset] = value & 0xFF
  while (++i < byteLength && (mul *= 0x100)) {
    this[offset + i] = (value / mul) & 0xFF
  }

  return offset + byteLength
}

Buffer.prototype.writeUIntBE = function writeUIntBE (value, offset, byteLength, noAssert) {
  value = +value
  offset = offset >>> 0
  byteLength = byteLength >>> 0
  if (!noAssert) {
    var maxBytes = Math.pow(2, 8 * byteLength) - 1
    checkInt(this, value, offset, byteLength, maxBytes, 0)
  }

  var i = byteLength - 1
  var mul = 1
  this[offset + i] = value & 0xFF
  while (--i >= 0 && (mul *= 0x100)) {
    this[offset + i] = (value / mul) & 0xFF
  }

  return offset + byteLength
}

Buffer.prototype.writeUInt8 = function writeUInt8 (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 1, 0xff, 0)
  this[offset] = (value & 0xff)
  return offset + 1
}

Buffer.prototype.writeUInt16LE = function writeUInt16LE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0)
  this[offset] = (value & 0xff)
  this[offset + 1] = (value >>> 8)
  return offset + 2
}

Buffer.prototype.writeUInt16BE = function writeUInt16BE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 2, 0xffff, 0)
  this[offset] = (value >>> 8)
  this[offset + 1] = (value & 0xff)
  return offset + 2
}

Buffer.prototype.writeUInt32LE = function writeUInt32LE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0)
  this[offset + 3] = (value >>> 24)
  this[offset + 2] = (value >>> 16)
  this[offset + 1] = (value >>> 8)
  this[offset] = (value & 0xff)
  return offset + 4
}

Buffer.prototype.writeUInt32BE = function writeUInt32BE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 4, 0xffffffff, 0)
  this[offset] = (value >>> 24)
  this[offset + 1] = (value >>> 16)
  this[offset + 2] = (value >>> 8)
  this[offset + 3] = (value & 0xff)
  return offset + 4
}

Buffer.prototype.writeIntLE = function writeIntLE (value, offset, byteLength, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) {
    var limit = Math.pow(2, (8 * byteLength) - 1)

    checkInt(this, value, offset, byteLength, limit - 1, -limit)
  }

  var i = 0
  var mul = 1
  var sub = 0
  this[offset] = value & 0xFF
  while (++i < byteLength && (mul *= 0x100)) {
    if (value < 0 && sub === 0 && this[offset + i - 1] !== 0) {
      sub = 1
    }
    this[offset + i] = ((value / mul) >> 0) - sub & 0xFF
  }

  return offset + byteLength
}

Buffer.prototype.writeIntBE = function writeIntBE (value, offset, byteLength, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) {
    var limit = Math.pow(2, (8 * byteLength) - 1)

    checkInt(this, value, offset, byteLength, limit - 1, -limit)
  }

  var i = byteLength - 1
  var mul = 1
  var sub = 0
  this[offset + i] = value & 0xFF
  while (--i >= 0 && (mul *= 0x100)) {
    if (value < 0 && sub === 0 && this[offset + i + 1] !== 0) {
      sub = 1
    }
    this[offset + i] = ((value / mul) >> 0) - sub & 0xFF
  }

  return offset + byteLength
}

Buffer.prototype.writeInt8 = function writeInt8 (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 1, 0x7f, -0x80)
  if (value < 0) value = 0xff + value + 1
  this[offset] = (value & 0xff)
  return offset + 1
}

Buffer.prototype.writeInt16LE = function writeInt16LE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000)
  this[offset] = (value & 0xff)
  this[offset + 1] = (value >>> 8)
  return offset + 2
}

Buffer.prototype.writeInt16BE = function writeInt16BE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 2, 0x7fff, -0x8000)
  this[offset] = (value >>> 8)
  this[offset + 1] = (value & 0xff)
  return offset + 2
}

Buffer.prototype.writeInt32LE = function writeInt32LE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000)
  this[offset] = (value & 0xff)
  this[offset + 1] = (value >>> 8)
  this[offset + 2] = (value >>> 16)
  this[offset + 3] = (value >>> 24)
  return offset + 4
}

Buffer.prototype.writeInt32BE = function writeInt32BE (value, offset, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) checkInt(this, value, offset, 4, 0x7fffffff, -0x80000000)
  if (value < 0) value = 0xffffffff + value + 1
  this[offset] = (value >>> 24)
  this[offset + 1] = (value >>> 16)
  this[offset + 2] = (value >>> 8)
  this[offset + 3] = (value & 0xff)
  return offset + 4
}

function checkIEEE754 (buf, value, offset, ext, max, min) {
  if (offset + ext > buf.length) throw new RangeError('Index out of range')
  if (offset < 0) throw new RangeError('Index out of range')
}

function writeFloat (buf, value, offset, littleEndian, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) {
    checkIEEE754(buf, value, offset, 4, 3.4028234663852886e+38, -3.4028234663852886e+38)
  }
  ieee754.write(buf, value, offset, littleEndian, 23, 4)
  return offset + 4
}

Buffer.prototype.writeFloatLE = function writeFloatLE (value, offset, noAssert) {
  return writeFloat(this, value, offset, true, noAssert)
}

Buffer.prototype.writeFloatBE = function writeFloatBE (value, offset, noAssert) {
  return writeFloat(this, value, offset, false, noAssert)
}

function writeDouble (buf, value, offset, littleEndian, noAssert) {
  value = +value
  offset = offset >>> 0
  if (!noAssert) {
    checkIEEE754(buf, value, offset, 8, 1.7976931348623157E+308, -1.7976931348623157E+308)
  }
  ieee754.write(buf, value, offset, littleEndian, 52, 8)
  return offset + 8
}

Buffer.prototype.writeDoubleLE = function writeDoubleLE (value, offset, noAssert) {
  return writeDouble(this, value, offset, true, noAssert)
}

Buffer.prototype.writeDoubleBE = function writeDoubleBE (value, offset, noAssert) {
  return writeDouble(this, value, offset, false, noAssert)
}

// copy(targetBuffer, targetStart=0, sourceStart=0, sourceEnd=buffer.length)
Buffer.prototype.copy = function copy (target, targetStart, start, end) {
  if (!Buffer.isBuffer(target)) throw new TypeError('argument should be a Buffer')
  if (!start) start = 0
  if (!end && end !== 0) end = this.length
  if (targetStart >= target.length) targetStart = target.length
  if (!targetStart) targetStart = 0
  if (end > 0 && end < start) end = start

  // Copy 0 bytes; we're done
  if (end === start) return 0
  if (target.length === 0 || this.length === 0) return 0

  // Fatal error conditions
  if (targetStart < 0) {
    throw new RangeError('targetStart out of bounds')
  }
  if (start < 0 || start >= this.length) throw new RangeError('Index out of range')
  if (end < 0) throw new RangeError('sourceEnd out of bounds')

  // Are we oob?
  if (end > this.length) end = this.length
  if (target.length - targetStart < end - start) {
    end = target.length - targetStart + start
  }

  var len = end - start

  if (this === target && typeof Uint8Array.prototype.copyWithin === 'function') {
    // Use built-in when available, missing from IE11
    this.copyWithin(targetStart, start, end)
  } else if (this === target && start < targetStart && targetStart < end) {
    // descending copy from end
    for (var i = len - 1; i >= 0; --i) {
      target[i + targetStart] = this[i + start]
    }
  } else {
    Uint8Array.prototype.set.call(
      target,
      this.subarray(start, end),
      targetStart
    )
  }

  return len
}

// Usage:
//    buffer.fill(number[, offset[, end]])
//    buffer.fill(buffer[, offset[, end]])
//    buffer.fill(string[, offset[, end]][, encoding])
Buffer.prototype.fill = function fill (val, start, end, encoding) {
  // Handle string cases:
  if (typeof val === 'string') {
    if (typeof start === 'string') {
      encoding = start
      start = 0
      end = this.length
    } else if (typeof end === 'string') {
      encoding = end
      end = this.length
    }
    if (encoding !== undefined && typeof encoding !== 'string') {
      throw new TypeError('encoding must be a string')
    }
    if (typeof encoding === 'string' && !Buffer.isEncoding(encoding)) {
      throw new TypeError('Unknown encoding: ' + encoding)
    }
    if (val.length === 1) {
      var code = val.charCodeAt(0)
      if ((encoding === 'utf8' && code < 128) ||
          encoding === 'latin1') {
        // Fast path: If `val` fits into a single byte, use that numeric value.
        val = code
      }
    }
  } else if (typeof val === 'number') {
    val = val & 255
  }

  // Invalid ranges are not set to a default, so can range check early.
  if (start < 0 || this.length < start || this.length < end) {
    throw new RangeError('Out of range index')
  }

  if (end <= start) {
    return this
  }

  start = start >>> 0
  end = end === undefined ? this.length : end >>> 0

  if (!val) val = 0

  var i
  if (typeof val === 'number') {
    for (i = start; i < end; ++i) {
      this[i] = val
    }
  } else {
    var bytes = Buffer.isBuffer(val)
      ? val
      : Buffer.from(val, encoding)
    var len = bytes.length
    if (len === 0) {
      throw new TypeError('The value "' + val +
        '" is invalid for argument "value"')
    }
    for (i = 0; i < end - start; ++i) {
      this[i + start] = bytes[i % len]
    }
  }

  return this
}

// HELPER FUNCTIONS
// ================

var INVALID_BASE64_RE = /[^+/0-9A-Za-z-_]/g

function base64clean (str) {
  // Node takes equal signs as end of the Base64 encoding
  str = str.split('=')[0]
  // Node strips out invalid characters like n and t from the string, base64-js does not
  str = str.trim().replace(INVALID_BASE64_RE, '')
  // Node converts strings with length < 2 to ''
  if (str.length < 2) return ''
  // Node allows for non-padded base64 strings (missing trailing ===), base64-js does not
  while (str.length % 4 !== 0) {
    str = str + '='
  }
  return str
}

function toHex (n) {
  if (n < 16) return '0' + n.toString(16)
  return n.toString(16)
}

function utf8ToBytes (string, units) {
  units = units || Infinity
  var codePoint
  var length = string.length
  var leadSurrogate = null
  var bytes = []

  for (var i = 0; i < length; ++i) {
    codePoint = string.charCodeAt(i)

    // is surrogate component
    if (codePoint > 0xD7FF && codePoint < 0xE000) {
      // last char was a lead
      if (!leadSurrogate) {
        // no lead yet
        if (codePoint > 0xDBFF) {
          // unexpected trail
          if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
          continue
        } else if (i + 1 === length) {
          // unpaired lead
          if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
          continue
        }

        // valid lead
        leadSurrogate = codePoint

        continue
      }

      // 2 leads in a row
      if (codePoint < 0xDC00) {
        if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
        leadSurrogate = codePoint
        continue
      }

      // valid surrogate pair
      codePoint = (leadSurrogate - 0xD800 << 10 | codePoint - 0xDC00) + 0x10000
    } else if (leadSurrogate) {
      // valid bmp char, but last char was a lead
      if ((units -= 3) > -1) bytes.push(0xEF, 0xBF, 0xBD)
    }

    leadSurrogate = null

    // encode utf8
    if (codePoint < 0x80) {
      if ((units -= 1) < 0) break
      bytes.push(codePoint)
    } else if (codePoint < 0x800) {
      if ((units -= 2) < 0) break
      bytes.push(
        codePoint >> 0x6 | 0xC0,
        codePoint & 0x3F | 0x80
      )
    } else if (codePoint < 0x10000) {
      if ((units -= 3) < 0) break
      bytes.push(
        codePoint >> 0xC | 0xE0,
        codePoint >> 0x6 & 0x3F | 0x80,
        codePoint & 0x3F | 0x80
      )
    } else if (codePoint < 0x110000) {
      if ((units -= 4) < 0) break
      bytes.push(
        codePoint >> 0x12 | 0xF0,
        codePoint >> 0xC & 0x3F | 0x80,
        codePoint >> 0x6 & 0x3F | 0x80,
        codePoint & 0x3F | 0x80
      )
    } else {
      throw new Error('Invalid code point')
    }
  }

  return bytes
}

function asciiToBytes (str) {
  var byteArray = []
  for (var i = 0; i < str.length; ++i) {
    // Node's code seems to be doing this and not & 0x7F..
    byteArray.push(str.charCodeAt(i) & 0xFF)
  }
  return byteArray
}

function utf16leToBytes (str, units) {
  var c, hi, lo
  var byteArray = []
  for (var i = 0; i < str.length; ++i) {
    if ((units -= 2) < 0) break

    c = str.charCodeAt(i)
    hi = c >> 8
    lo = c % 256
    byteArray.push(lo)
    byteArray.push(hi)
  }

  return byteArray
}

function base64ToBytes (str) {
  return base64.toByteArray(base64clean(str))
}

function blitBuffer (src, dst, offset, length) {
  for (var i = 0; i < length; ++i) {
    if ((i + offset >= dst.length) || (i >= src.length)) break
    dst[i + offset] = src[i]
  }
  return i
}

// ArrayBuffer or Uint8Array objects from other contexts (i.e. iframes) do not pass
// the `instanceof` check but they should be treated as of that type.
// See: https://github.com/feross/buffer/issues/166
function isInstance (obj, type) {
  return obj instanceof type ||
    (obj != null && obj.constructor != null && obj.constructor.name != null &&
      obj.constructor.name === type.name)
}
function numberIsNaN (obj) {
  // For IE11 support
  return obj !== obj // eslint-disable-line no-self-compare
}

}).call(this,require("buffer").Buffer)
},{"base64-js":1,"buffer":3,"ieee754":7}],4:[function(require,module,exports){
(function (Buffer){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

// NOTE: These type checking functions intentionally don't use `instanceof`
// because it is fragile and can be easily faked with `Object.create()`.

function isArray(arg) {
  if (Array.isArray) {
    return Array.isArray(arg);
  }
  return objectToString(arg) === '[object Array]';
}
exports.isArray = isArray;

function isBoolean(arg) {
  return typeof arg === 'boolean';
}
exports.isBoolean = isBoolean;

function isNull(arg) {
  return arg === null;
}
exports.isNull = isNull;

function isNullOrUndefined(arg) {
  return arg == null;
}
exports.isNullOrUndefined = isNullOrUndefined;

function isNumber(arg) {
  return typeof arg === 'number';
}
exports.isNumber = isNumber;

function isString(arg) {
  return typeof arg === 'string';
}
exports.isString = isString;

function isSymbol(arg) {
  return typeof arg === 'symbol';
}
exports.isSymbol = isSymbol;

function isUndefined(arg) {
  return arg === void 0;
}
exports.isUndefined = isUndefined;

function isRegExp(re) {
  return objectToString(re) === '[object RegExp]';
}
exports.isRegExp = isRegExp;

function isObject(arg) {
  return typeof arg === 'object' && arg !== null;
}
exports.isObject = isObject;

function isDate(d) {
  return objectToString(d) === '[object Date]';
}
exports.isDate = isDate;

function isError(e) {
  return (objectToString(e) === '[object Error]' || e instanceof Error);
}
exports.isError = isError;

function isFunction(arg) {
  return typeof arg === 'function';
}
exports.isFunction = isFunction;

function isPrimitive(arg) {
  return arg === null ||
         typeof arg === 'boolean' ||
         typeof arg === 'number' ||
         typeof arg === 'string' ||
         typeof arg === 'symbol' ||  // ES6 symbol
         typeof arg === 'undefined';
}
exports.isPrimitive = isPrimitive;

exports.isBuffer = Buffer.isBuffer;

function objectToString(o) {
  return Object.prototype.toString.call(o);
}

}).call(this,{"isBuffer":require("../../is-buffer/index.js")})
},{"../../is-buffer/index.js":9}],5:[function(require,module,exports){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

var objectCreate = Object.create || objectCreatePolyfill
var objectKeys = Object.keys || objectKeysPolyfill
var bind = Function.prototype.bind || functionBindPolyfill

function EventEmitter() {
  if (!this._events || !Object.prototype.hasOwnProperty.call(this, '_events')) {
    this._events = objectCreate(null);
    this._eventsCount = 0;
  }

  this._maxListeners = this._maxListeners || undefined;
}
module.exports = EventEmitter;

// Backwards-compat with node 0.10.x
EventEmitter.EventEmitter = EventEmitter;

EventEmitter.prototype._events = undefined;
EventEmitter.prototype._maxListeners = undefined;

// By default EventEmitters will print a warning if more than 10 listeners are
// added to it. This is a useful default which helps finding memory leaks.
var defaultMaxListeners = 10;

var hasDefineProperty;
try {
  var o = {};
  if (Object.defineProperty) Object.defineProperty(o, 'x', { value: 0 });
  hasDefineProperty = o.x === 0;
} catch (err) { hasDefineProperty = false }
if (hasDefineProperty) {
  Object.defineProperty(EventEmitter, 'defaultMaxListeners', {
    enumerable: true,
    get: function() {
      return defaultMaxListeners;
    },
    set: function(arg) {
      // check whether the input is a positive number (whose value is zero or
      // greater and not a NaN).
      if (typeof arg !== 'number' || arg < 0 || arg !== arg)
        throw new TypeError('"defaultMaxListeners" must be a positive number');
      defaultMaxListeners = arg;
    }
  });
} else {
  EventEmitter.defaultMaxListeners = defaultMaxListeners;
}

// Obviously not all Emitters should be limited to 10. This function allows
// that to be increased. Set to zero for unlimited.
EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
  if (typeof n !== 'number' || n < 0 || isNaN(n))
    throw new TypeError('"n" argument must be a positive number');
  this._maxListeners = n;
  return this;
};

function $getMaxListeners(that) {
  if (that._maxListeners === undefined)
    return EventEmitter.defaultMaxListeners;
  return that._maxListeners;
}

EventEmitter.prototype.getMaxListeners = function getMaxListeners() {
  return $getMaxListeners(this);
};

// These standalone emit* functions are used to optimize calling of event
// handlers for fast cases because emit() itself often has a variable number of
// arguments and can be deoptimized because of that. These functions always have
// the same number of arguments and thus do not get deoptimized, so the code
// inside them can execute faster.
function emitNone(handler, isFn, self) {
  if (isFn)
    handler.call(self);
  else {
    var len = handler.length;
    var listeners = arrayClone(handler, len);
    for (var i = 0; i < len; ++i)
      listeners[i].call(self);
  }
}
function emitOne(handler, isFn, self, arg1) {
  if (isFn)
    handler.call(self, arg1);
  else {
    var len = handler.length;
    var listeners = arrayClone(handler, len);
    for (var i = 0; i < len; ++i)
      listeners[i].call(self, arg1);
  }
}
function emitTwo(handler, isFn, self, arg1, arg2) {
  if (isFn)
    handler.call(self, arg1, arg2);
  else {
    var len = handler.length;
    var listeners = arrayClone(handler, len);
    for (var i = 0; i < len; ++i)
      listeners[i].call(self, arg1, arg2);
  }
}
function emitThree(handler, isFn, self, arg1, arg2, arg3) {
  if (isFn)
    handler.call(self, arg1, arg2, arg3);
  else {
    var len = handler.length;
    var listeners = arrayClone(handler, len);
    for (var i = 0; i < len; ++i)
      listeners[i].call(self, arg1, arg2, arg3);
  }
}

function emitMany(handler, isFn, self, args) {
  if (isFn)
    handler.apply(self, args);
  else {
    var len = handler.length;
    var listeners = arrayClone(handler, len);
    for (var i = 0; i < len; ++i)
      listeners[i].apply(self, args);
  }
}

EventEmitter.prototype.emit = function emit(type) {
  var er, handler, len, args, i, events;
  var doError = (type === 'error');

  events = this._events;
  if (events)
    doError = (doError && events.error == null);
  else if (!doError)
    return false;

  // If there is no 'error' event listener then throw.
  if (doError) {
    if (arguments.length > 1)
      er = arguments[1];
    if (er instanceof Error) {
      throw er; // Unhandled 'error' event
    } else {
      // At least give some kind of context to the user
      var err = new Error('Unhandled "error" event. (' + er + ')');
      err.context = er;
      throw err;
    }
    return false;
  }

  handler = events[type];

  if (!handler)
    return false;

  var isFn = typeof handler === 'function';
  len = arguments.length;
  switch (len) {
      // fast cases
    case 1:
      emitNone(handler, isFn, this);
      break;
    case 2:
      emitOne(handler, isFn, this, arguments[1]);
      break;
    case 3:
      emitTwo(handler, isFn, this, arguments[1], arguments[2]);
      break;
    case 4:
      emitThree(handler, isFn, this, arguments[1], arguments[2], arguments[3]);
      break;
      // slower
    default:
      args = new Array(len - 1);
      for (i = 1; i < len; i++)
        args[i - 1] = arguments[i];
      emitMany(handler, isFn, this, args);
  }

  return true;
};

function _addListener(target, type, listener, prepend) {
  var m;
  var events;
  var existing;

  if (typeof listener !== 'function')
    throw new TypeError('"listener" argument must be a function');

  events = target._events;
  if (!events) {
    events = target._events = objectCreate(null);
    target._eventsCount = 0;
  } else {
    // To avoid recursion in the case that type === "newListener"! Before
    // adding it to the listeners, first emit "newListener".
    if (events.newListener) {
      target.emit('newListener', type,
          listener.listener ? listener.listener : listener);

      // Re-assign `events` because a newListener handler could have caused the
      // this._events to be assigned to a new object
      events = target._events;
    }
    existing = events[type];
  }

  if (!existing) {
    // Optimize the case of one listener. Don't need the extra array object.
    existing = events[type] = listener;
    ++target._eventsCount;
  } else {
    if (typeof existing === 'function') {
      // Adding the second element, need to change to array.
      existing = events[type] =
          prepend ? [listener, existing] : [existing, listener];
    } else {
      // If we've already got an array, just append.
      if (prepend) {
        existing.unshift(listener);
      } else {
        existing.push(listener);
      }
    }

    // Check for listener leak
    if (!existing.warned) {
      m = $getMaxListeners(target);
      if (m && m > 0 && existing.length > m) {
        existing.warned = true;
        var w = new Error('Possible EventEmitter memory leak detected. ' +
            existing.length + ' "' + String(type) + '" listeners ' +
            'added. Use emitter.setMaxListeners() to ' +
            'increase limit.');
        w.name="MaxListenersExceededWarning";
        w.emitter = target;
        w.type = type;
        w.count = existing.length;
        if (typeof console === 'object' && console.warn) {
          console.warn('%s: %s', w.name, w.message);
        }
      }
    }
  }

  return target;
}

EventEmitter.prototype.addListener = function addListener(type, listener) {
  return _addListener(this, type, listener, false);
};

EventEmitter.prototype.on = EventEmitter.prototype.addListener;

EventEmitter.prototype.prependListener =
    function prependListener(type, listener) {
      return _addListener(this, type, listener, true);
    };

function onceWrapper() {
  if (!this.fired) {
    this.target.removeListener(this.type, this.wrapFn);
    this.fired = true;
    switch (arguments.length) {
      case 0:
        return this.listener.call(this.target);
      case 1:
        return this.listener.call(this.target, arguments[0]);
      case 2:
        return this.listener.call(this.target, arguments[0], arguments[1]);
      case 3:
        return this.listener.call(this.target, arguments[0], arguments[1],
            arguments[2]);
      default:
        var args = new Array(arguments.length);
        for (var i = 0; i < args.length; ++i)
          args[i] = arguments[i];
        this.listener.apply(this.target, args);
    }
  }
}

function _onceWrap(target, type, listener) {
  var state = { fired: false, wrapFn: undefined, target: target, type: type, listener: listener };
  var wrapped = bind.call(onceWrapper, state);
  wrapped.listener = listener;
  state.wrapFn = wrapped;
  return wrapped;
}

EventEmitter.prototype.once = function once(type, listener) {
  if (typeof listener !== 'function')
    throw new TypeError('"listener" argument must be a function');
  this.on(type, _onceWrap(this, type, listener));
  return this;
};

EventEmitter.prototype.prependOnceListener =
    function prependOnceListener(type, listener) {
      if (typeof listener !== 'function')
        throw new TypeError('"listener" argument must be a function');
      this.prependListener(type, _onceWrap(this, type, listener));
      return this;
    };

// Emits a 'removeListener' event if and only if the listener was removed.
EventEmitter.prototype.removeListener =
    function removeListener(type, listener) {
      var list, events, position, i, originalListener;

      if (typeof listener !== 'function')
        throw new TypeError('"listener" argument must be a function');

      events = this._events;
      if (!events)
        return this;

      list = events[type];
      if (!list)
        return this;

      if (list === listener || list.listener === listener) {
        if (--this._eventsCount === 0)
          this._events = objectCreate(null);
        else {
          delete events[type];
          if (events.removeListener)
            this.emit('removeListener', type, list.listener || listener);
        }
      } else if (typeof list !== 'function') {
        position = -1;

        for (i = list.length - 1; i >= 0; i--) {
          if (list[i] === listener || list[i].listener === listener) {
            originalListener = list[i].listener;
            position = i;
            break;
          }
        }

        if (position < 0)
          return this;

        if (position === 0)
          list.shift();
        else
          spliceOne(list, position);

        if (list.length === 1)
          events[type] = list[0];

        if (events.removeListener)
          this.emit('removeListener', type, originalListener || listener);
      }

      return this;
    };

EventEmitter.prototype.removeAllListeners =
    function removeAllListeners(type) {
      var listeners, events, i;

      events = this._events;
      if (!events)
        return this;

      // not listening for removeListener, no need to emit
      if (!events.removeListener) {
        if (arguments.length === 0) {
          this._events = objectCreate(null);
          this._eventsCount = 0;
        } else if (events[type]) {
          if (--this._eventsCount === 0)
            this._events = objectCreate(null);
          else
            delete events[type];
        }
        return this;
      }

      // emit removeListener for all listeners on all events
      if (arguments.length === 0) {
        var keys = objectKeys(events);
        var key;
        for (i = 0; i < keys.length; ++i) {
          key = keys[i];
          if (key === 'removeListener') continue;
          this.removeAllListeners(key);
        }
        this.removeAllListeners('removeListener');
        this._events = objectCreate(null);
        this._eventsCount = 0;
        return this;
      }

      listeners = events[type];

      if (typeof listeners === 'function') {
        this.removeListener(type, listeners);
      } else if (listeners) {
        // LIFO order
        for (i = listeners.length - 1; i >= 0; i--) {
          this.removeListener(type, listeners[i]);
        }
      }

      return this;
    };

function _listeners(target, type, unwrap) {
  var events = target._events;

  if (!events)
    return [];

  var evlistener = events[type];
  if (!evlistener)
    return [];

  if (typeof evlistener === 'function')
    return unwrap ? [evlistener.listener || evlistener] : [evlistener];

  return unwrap ? unwrapListeners(evlistener) : arrayClone(evlistener, evlistener.length);
}

EventEmitter.prototype.listeners = function listeners(type) {
  return _listeners(this, type, true);
};

EventEmitter.prototype.rawListeners = function rawListeners(type) {
  return _listeners(this, type, false);
};

EventEmitter.listenerCount = function(emitter, type) {
  if (typeof emitter.listenerCount === 'function') {
    return emitter.listenerCount(type);
  } else {
    return listenerCount.call(emitter, type);
  }
};

EventEmitter.prototype.listenerCount = listenerCount;
function listenerCount(type) {
  var events = this._events;

  if (events) {
    var evlistener = events[type];

    if (typeof evlistener === 'function') {
      return 1;
    } else if (evlistener) {
      return evlistener.length;
    }
  }

  return 0;
}

EventEmitter.prototype.eventNames = function eventNames() {
  return this._eventsCount > 0 ? Reflect.ownKeys(this._events) : [];
};

// About 1.5x faster than the two-arg version of Array#splice().
function spliceOne(list, index) {
  for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
    list[i] = list[k];
  list.pop();
}

function arrayClone(arr, n) {
  var copy = new Array(n);
  for (var i = 0; i < n; ++i)
    copy[i] = arr[i];
  return copy;
}

function unwrapListeners(arr) {
  var ret = new Array(arr.length);
  for (var i = 0; i < ret.length; ++i) {
    ret[i] = arr[i].listener || arr[i];
  }
  return ret;
}

function objectCreatePolyfill(proto) {
  var F = function() {};
  F.prototype = proto;
  return new F;
}
function objectKeysPolyfill(obj) {
  var keys = [];
  for (var k in obj) if (Object.prototype.hasOwnProperty.call(obj, k)) {
    keys.push(k);
  }
  return k;
}
function functionBindPolyfill(context) {
  var fn = this;
  return function () {
    return fn.apply(context, arguments);
  };
}

},{}],6:[function(require,module,exports){
// originally pulled out of simple-peer

module.exports = function getBrowserRTC () {
  if (typeof window === 'undefined') return null
  var wrtc = {
    RTCPeerConnection: window.RTCPeerConnection || window.mozRTCPeerConnection ||
      window.webkitRTCPeerConnection,
    RTCSessionDescription: window.RTCSessionDescription ||
      window.mozRTCSessionDescription || window.webkitRTCSessionDescription,
    RTCIceCandidate: window.RTCIceCandidate || window.mozRTCIceCandidate ||
      window.webkitRTCIceCandidate
  }
  if (!wrtc.RTCPeerConnection) return null
  return wrtc
}

},{}],7:[function(require,module,exports){
exports.read = function (buffer, offset, isLE, mLen, nBytes) {
  var e, m
  var eLen = (nBytes * 8) - mLen - 1
  var eMax = (1 << eLen) - 1
  var eBias = eMax >> 1
  var nBits = -7
  var i = isLE ? (nBytes - 1) : 0
  var d = isLE ? -1 : 1
  var s = buffer[offset + i]

  i += d

  e = s & ((1 << (-nBits)) - 1)
  s >>= (-nBits)
  nBits += eLen
  for (; nBits > 0; e = (e * 256) + buffer[offset + i], i += d, nBits -= 8) {}

  m = e & ((1 << (-nBits)) - 1)
  e >>= (-nBits)
  nBits += mLen
  for (; nBits > 0; m = (m * 256) + buffer[offset + i], i += d, nBits -= 8) {}

  if (e === 0) {
    e = 1 - eBias
  } else if (e === eMax) {
    return m ? NaN : ((s ? -1 : 1) * Infinity)
  } else {
    m = m + Math.pow(2, mLen)
    e = e - eBias
  }
  return (s ? -1 : 1) * m * Math.pow(2, e - mLen)
}

exports.write = function (buffer, value, offset, isLE, mLen, nBytes) {
  var e, m, c
  var eLen = (nBytes * 8) - mLen - 1
  var eMax = (1 << eLen) - 1
  var eBias = eMax >> 1
  var rt = (mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0)
  var i = isLE ? 0 : (nBytes - 1)
  var d = isLE ? 1 : -1
  var s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0

  value = Math.abs(value)

  if (isNaN(value) || value === Infinity) {
    m = isNaN(value) ? 1 : 0
    e = eMax
  } else {
    e = Math.floor(Math.log(value) / Math.LN2)
    if (value * (c = Math.pow(2, -e)) < 1) {
      e--
      c *= 2
    }
    if (e + eBias >= 1) {
      value += rt / c
    } else {
      value += rt * Math.pow(2, 1 - eBias)
    }
    if (value * c >= 2) {
      e++
      c /= 2
    }

    if (e + eBias >= eMax) {
      m = 0
      e = eMax
    } else if (e + eBias >= 1) {
      m = ((value * c) - 1) * Math.pow(2, mLen)
      e = e + eBias
    } else {
      m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen)
      e = 0
    }
  }

  for (; mLen >= 8; buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8) {}

  e = (e << mLen) | m
  eLen += mLen
  for (; eLen > 0; buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8) {}

  buffer[offset + i - d] |= s * 128
}

},{}],8:[function(require,module,exports){
if (typeof Object.create === 'function') {
  // implementation from standard node.js 'util' module
  module.exports = function inherits(ctor, superCtor) {
    ctor.super_ = superCtor
    ctor.prototype = Object.create(superCtor.prototype, {
      constructor: {
        value: ctor,
        enumerable: false,
        writable: true,
        configurable: true
      }
    });
  };
} else {
  // old school shim for old browsers
  module.exports = function inherits(ctor, superCtor) {
    ctor.super_ = superCtor
    var TempCtor = function () {}
    TempCtor.prototype = superCtor.prototype
    ctor.prototype = new TempCtor()
    ctor.prototype.constructor = ctor
  }
}

},{}],9:[function(require,module,exports){
/*!
 * Determine if an object is a Buffer
 *
 * @author   Feross Aboukhadijeh <https://feross.org>
 * @license  MIT
 */

// The _isBuffer check is for Safari 5-7 support, because it's missing
// Object.prototype.constructor. Remove this eventually
module.exports = function (obj) {
  return obj != null && (isBuffer(obj) || isSlowBuffer(obj) || !!obj._isBuffer)
}

function isBuffer (obj) {
  return !!obj.constructor && typeof obj.constructor.isBuffer === 'function' && obj.constructor.isBuffer(obj)
}

// For Node v0.10 support. Remove this eventually.
function isSlowBuffer (obj) {
  return typeof obj.readFloatLE === 'function' && typeof obj.slice === 'function' && isBuffer(obj.slice(0, 0))
}

},{}],10:[function(require,module,exports){
var toString = {}.toString;

module.exports = Array.isArray || function (arr) {
  return toString.call(arr) == '[object Array]';
};

},{}],11:[function(require,module,exports){
(function (process){
'use strict';

if (!process.version ||
    process.version.indexOf('v0.') === 0 ||
    process.version.indexOf('v1.') === 0 && process.version.indexOf('v1.8.') !== 0) {
  module.exports = { nextTick: nextTick };
} else {
  module.exports = process
}

function nextTick(fn, arg1, arg2, arg3) {
  if (typeof fn !== 'function') {
    throw new TypeError('"callback" argument must be a function');
  }
  var len = arguments.length;
  var args, i;
  switch (len) {
  case 0:
  case 1:
    return process.nextTick(fn);
  case 2:
    return process.nextTick(function afterTickOne() {
      fn.call(null, arg1);
    });
  case 3:
    return process.nextTick(function afterTickTwo() {
      fn.call(null, arg1, arg2);
    });
  case 4:
    return process.nextTick(function afterTickThree() {
      fn.call(null, arg1, arg2, arg3);
    });
  default:
    args = new Array(len - 1);
    i = 0;
    while (i < args.length) {
      args[i++] = arguments[i];
    }
    return process.nextTick(function afterTick() {
      fn.apply(null, args);
    });
  }
}


}).call(this,require('_process'))
},{"_process":12}],12:[function(require,module,exports){
// shim for using process in browser
var process = module.exports = {};

// cached from whatever global is present so that test runners that stub it
// don't break things.  But we need to wrap it in a try catch in case it is
// wrapped in strict mode code which doesn't define any globals.  It's inside a
// function because try/catches deoptimize in certain engines.

var cachedSetTimeout;
var cachedClearTimeout;

function defaultSetTimout() {
    throw new Error('setTimeout has not been defined');
}
function defaultClearTimeout () {
    throw new Error('clearTimeout has not been defined');
}
(function () {
    try {
        if (typeof setTimeout === 'function') {
            cachedSetTimeout = setTimeout;
        } else {
            cachedSetTimeout = defaultSetTimout;
        }
    } catch (e) {
        cachedSetTimeout = defaultSetTimout;
    }
    try {
        if (typeof clearTimeout === 'function') {
            cachedClearTimeout = clearTimeout;
        } else {
            cachedClearTimeout = defaultClearTimeout;
        }
    } catch (e) {
        cachedClearTimeout = defaultClearTimeout;
    }
} ())
function runTimeout(fun) {
    if (cachedSetTimeout === setTimeout) {
        //normal enviroments in sane situations
        return setTimeout(fun, 0);
    }
    // if setTimeout wasn't available but was latter defined
    if ((cachedSetTimeout === defaultSetTimout || !cachedSetTimeout) && setTimeout) {
        cachedSetTimeout = setTimeout;
        return setTimeout(fun, 0);
    }
    try {
        // when when somebody has screwed with setTimeout but no I.E. maddness
        return cachedSetTimeout(fun, 0);
    } catch(e){
        try {
            // When we are in I.E. but the script has been evaled so I.E. doesn't trust the global object when called normally
            return cachedSetTimeout.call(null, fun, 0);
        } catch(e){
            // same as above but when it's a version of I.E. that must have the global object for 'this', hopfully our context correct otherwise it will throw a global error
            return cachedSetTimeout.call(this, fun, 0);
        }
    }


}
function runClearTimeout(marker) {
    if (cachedClearTimeout === clearTimeout) {
        //normal enviroments in sane situations
        return clearTimeout(marker);
    }
    // if clearTimeout wasn't available but was latter defined
    if ((cachedClearTimeout === defaultClearTimeout || !cachedClearTimeout) && clearTimeout) {
        cachedClearTimeout = clearTimeout;
        return clearTimeout(marker);
    }
    try {
        // when when somebody has screwed with setTimeout but no I.E. maddness
        return cachedClearTimeout(marker);
    } catch (e){
        try {
            // When we are in I.E. but the script has been evaled so I.E. doesn't  trust the global object when called normally
            return cachedClearTimeout.call(null, marker);
        } catch (e){
            // same as above but when it's a version of I.E. that must have the global object for 'this', hopfully our context correct otherwise it will throw a global error.
            // Some versions of I.E. have different rules for clearTimeout vs setTimeout
            return cachedClearTimeout.call(this, marker);
        }
    }



}
var queue = [];
var draining = false;
var currentQueue;
var queueIndex = -1;

function cleanUpNextTick() {
    if (!draining || !currentQueue) {
        return;
    }
    draining = false;
    if (currentQueue.length) {
        queue = currentQueue.concat(queue);
    } else {
        queueIndex = -1;
    }
    if (queue.length) {
        drainQueue();
    }
}

function drainQueue() {
    if (draining) {
        return;
    }
    var timeout = runTimeout(cleanUpNextTick);
    draining = true;

    var len = queue.length;
    while(len) {
        currentQueue = queue;
        queue = [];
        while (++queueIndex < len) {
            if (currentQueue) {
                currentQueue[queueIndex].run();
            }
        }
        queueIndex = -1;
        len = queue.length;
    }
    currentQueue = null;
    draining = false;
    runClearTimeout(timeout);
}

process.nextTick = function (fun) {
    var args = new Array(arguments.length - 1);
    if (arguments.length > 1) {
        for (var i = 1; i < arguments.length; i++) {
            args[i - 1] = arguments[i];
        }
    }
    queue.push(new Item(fun, args));
    if (queue.length === 1 && !draining) {
        runTimeout(drainQueue);
    }
};

// v8 likes predictible objects
function Item(fun, array) {
    this.fun = fun;
    this.array = array;
}
Item.prototype.run = function () {
    this.fun.apply(null, this.array);
};
process.title="browser";
process.browser = true;
process.env = {};
process.argv = [];
process.version = ''; // empty string to avoid regexp issues
process.versions = {};

function noop() {}

process.on = noop;
process.addListener = noop;
process.once = noop;
process.off = noop;
process.removeListener = noop;
process.removeAllListeners = noop;
process.emit = noop;
process.prependListener = noop;
process.prependOnceListener = noop;

process.listeners = function (name) { return [] }

process.binding = function (name) {
    throw new Error('process.binding is not supported');
};

process.cwd = function () { return '/' };
process.chdir = function (dir) {
    throw new Error('process.chdir is not supported');
};
process.umask = function() { return 0; };

},{}],13:[function(require,module,exports){
(function (process,global){
'use strict'

// limit of Crypto.getRandomValues()
// https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
var MAX_BYTES = 65536

// Node supports requesting up to this number of bytes
// https://github.com/nodejs/node/blob/master/lib/internal/crypto/random.js#L48
var MAX_UINT32 = 4294967295

function oldBrowser () {
  throw new Error('Secure random number generation is not supported by this browser.nUse Chrome, Firefox or Internet Explorer 11')
}

var Buffer = require('safe-buffer').Buffer
var crypto = global.crypto || global.msCrypto

if (crypto && crypto.getRandomValues) {
  module.exports = randomBytes
} else {
  module.exports = oldBrowser
}

function randomBytes (size, cb) {
  // phantomjs needs to throw
  if (size > MAX_UINT32) throw new RangeError('requested too many random bytes')

  var bytes = Buffer.allocUnsafe(size)

  if (size > 0) {  // getRandomValues fails on IE if size == 0
    if (size > MAX_BYTES) { // this is the max bytes crypto.getRandomValues
      // can do at once see https://developer.mozilla.org/en-US/docs/Web/API/window.crypto.getRandomValues
      for (var generated = 0; generated < size; generated += MAX_BYTES) {
        // buffer.slice automatically checks if the end is past the end of
        // the buffer so we don't have to here
        crypto.getRandomValues(bytes.slice(generated, generated + MAX_BYTES))
      }
    } else {
      crypto.getRandomValues(bytes)
    }
  }

  if (typeof cb === 'function') {
    return process.nextTick(function () {
      cb(null, bytes)
    })
  }

  return bytes
}

}).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
},{"_process":12,"safe-buffer":23}],14:[function(require,module,exports){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

// a duplex stream is just a stream that is both readable and writable.
// Since JS doesn't have multiple prototypal inheritance, this class
// prototypally inherits from Readable, and then parasitically from
// Writable.

'use strict';

/*<replacement>*/

var pna = require('process-nextick-args');
/*</replacement>*/

/*<replacement>*/
var objectKeys = Object.keys || function (obj) {
  var keys = [];
  for (var key in obj) {
    keys.push(key);
  }return keys;
};
/*</replacement>*/

module.exports = Duplex;

/*<replacement>*/
var util = require('core-util-is');
util.inherits = require('inherits');
/*</replacement>*/

var Readable = require('./_stream_readable');
var Writable = require('./_stream_writable');

util.inherits(Duplex, Readable);

{
  // avoid scope creep, the keys array can then be collected
  var keys = objectKeys(Writable.prototype);
  for (var v = 0; v < keys.length; v++) {
    var method = keys[v];
    if (!Duplex.prototype[method]) Duplex.prototype[method] = Writable.prototype[method];
  }
}

function Duplex(options) {
  if (!(this instanceof Duplex)) return new Duplex(options);

  Readable.call(this, options);
  Writable.call(this, options);

  if (options && options.readable === false) this.readable = false;

  if (options && options.writable === false) this.writable = false;

  this.allowHalfOpen = true;
  if (options && options.allowHalfOpen === false) this.allowHalfOpen = false;

  this.once('end', onend);
}

Object.defineProperty(Duplex.prototype, 'writableHighWaterMark', {
  // making it explicit this property is not enumerable
  // because otherwise some prototype manipulation in
  // userland will fail
  enumerable: false,
  get: function () {
    return this._writableState.highWaterMark;
  }
});

// the no-half-open enforcer
function onend() {
  // if we allow half-open state, or if the writable side ended,
  // then we're ok.
  if (this.allowHalfOpen || this._writableState.ended) return;

  // no more data can be written.
  // But allow more writes to happen in this tick.
  pna.nextTick(onEndNT, this);
}

function onEndNT(self) {
  self.end();
}

Object.defineProperty(Duplex.prototype, 'destroyed', {
  get: function () {
    if (this._readableState === undefined || this._writableState === undefined) {
      return false;
    }
    return this._readableState.destroyed && this._writableState.destroyed;
  },
  set: function (value) {
    // we ignore the value if the stream
    // has not been initialized yet
    if (this._readableState === undefined || this._writableState === undefined) {
      return;
    }

    // backward compatibility, the user is explicitly
    // managing destroyed
    this._readableState.destroyed = value;
    this._writableState.destroyed = value;
  }
});

Duplex.prototype._destroy = function (err, cb) {
  this.push(null);
  this.end();

  pna.nextTick(cb, err);
};
},{"./_stream_readable":16,"./_stream_writable":18,"core-util-is":4,"inherits":8,"process-nextick-args":11}],15:[function(require,module,exports){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

// a passthrough stream.
// basically just the most minimal sort of Transform stream.
// Every written chunk gets output as-is.

'use strict';

module.exports = PassThrough;

var Transform = require('./_stream_transform');

/*<replacement>*/
var util = require('core-util-is');
util.inherits = require('inherits');
/*</replacement>*/

util.inherits(PassThrough, Transform);

function PassThrough(options) {
  if (!(this instanceof PassThrough)) return new PassThrough(options);

  Transform.call(this, options);
}

PassThrough.prototype._transform = function (chunk, encoding, cb) {
  cb(null, chunk);
};
},{"./_stream_transform":17,"core-util-is":4,"inherits":8}],16:[function(require,module,exports){
(function (process,global){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';

/*<replacement>*/

var pna = require('process-nextick-args');
/*</replacement>*/

module.exports = Readable;

/*<replacement>*/
var isArray = require('isarray');
/*</replacement>*/

/*<replacement>*/
var Duplex;
/*</replacement>*/

Readable.ReadableState = ReadableState;

/*<replacement>*/
var EE = require('events').EventEmitter;

var EElistenerCount = function (emitter, type) {
  return emitter.listeners(type).length;
};
/*</replacement>*/

/*<replacement>*/
var Stream = require('./internal/streams/stream');
/*</replacement>*/

/*<replacement>*/

var Buffer = require('safe-buffer').Buffer;
var OurUint8Array = global.Uint8Array || function () {};
function _uint8ArrayToBuffer(chunk) {
  return Buffer.from(chunk);
}
function _isUint8Array(obj) {
  return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
}

/*</replacement>*/

/*<replacement>*/
var util = require('core-util-is');
util.inherits = require('inherits');
/*</replacement>*/

/*<replacement>*/
var debugUtil = require('util');
var debug = void 0;
if (debugUtil && debugUtil.debuglog) {
  debug = debugUtil.debuglog('stream');
} else {
  debug = function () {};
}
/*</replacement>*/

var BufferList = require('./internal/streams/BufferList');
var destroyImpl = require('./internal/streams/destroy');
var StringDecoder;

util.inherits(Readable, Stream);

var kProxyEvents = ['error', 'close', 'destroy', 'pause', 'resume'];

function prependListener(emitter, event, fn) {
  // Sadly this is not cacheable as some libraries bundle their own
  // event emitter implementation with them.
  if (typeof emitter.prependListener === 'function') return emitter.prependListener(event, fn);

  // This is a hack to make sure that our error handler is attached before any
  // userland ones.  NEVER DO THIS. This is here only because this code needs
  // to continue to work with older versions of Node.js that do not include
  // the prependListener() method. The goal is to eventually remove this hack.
  if (!emitter._events || !emitter._events[event]) emitter.on(event, fn);else if (isArray(emitter._events[event])) emitter._events[event].unshift(fn);else emitter._events[event] = [fn, emitter._events[event]];
}

function ReadableState(options, stream) {
  Duplex = Duplex || require('./_stream_duplex');

  options = options || {};

  // Duplex streams are both readable and writable, but share
  // the same options object.
  // However, some cases require setting options to different
  // values for the readable and the writable sides of the duplex stream.
  // These options can be provided separately as readableXXX and writableXXX.
  var isDuplex = stream instanceof Duplex;

  // object stream flag. Used to make read(n) ignore n and to
  // make all the buffer merging and length checks go away
  this.objectMode = !!options.objectMode;

  if (isDuplex) this.objectMode = this.objectMode || !!options.readableObjectMode;

  // the point at which it stops calling _read() to fill the buffer
  // Note: 0 is a valid value, means "don't call _read preemptively ever"
  var hwm = options.highWaterMark;
  var readableHwm = options.readableHighWaterMark;
  var defaultHwm = this.objectMode ? 16 : 16 * 1024;

  if (hwm || hwm === 0) this.highWaterMark = hwm;else if (isDuplex && (readableHwm || readableHwm === 0)) this.highWaterMark = readableHwm;else this.highWaterMark = defaultHwm;

  // cast to ints.
  this.highWaterMark = Math.floor(this.highWaterMark);

  // A linked list is used to store data chunks instead of an array because the
  // linked list can remove elements from the beginning faster than
  // array.shift()
  this.buffer = new BufferList();
  this.length = 0;
  this.pipes = null;
  this.pipesCount = 0;
  this.flowing = null;
  this.ended = false;
  this.endEmitted = false;
  this.reading = false;

  // a flag to be able to tell if the event 'readable'/'data' is emitted
  // immediately, or on a later tick.  We set this to true at first, because
  // any actions that shouldn't happen until "later" should generally also
  // not happen before the first read call.
  this.sync = true;

  // whenever we return null, then we set a flag to say
  // that we're awaiting a 'readable' event emission.
  this.needReadable = false;
  this.emittedReadable = false;
  this.readableListening = false;
  this.resumeScheduled = false;

  // has it been destroyed
  this.destroyed = false;

  // Crypto is kind of old and crusty.  Historically, its default string
  // encoding is 'binary' so we have to make this configurable.
  // Everything else in the universe uses 'utf8', though.
  this.defaultEncoding = options.defaultEncoding || 'utf8';

  // the number of writers that are awaiting a drain event in .pipe()s
  this.awaitDrain = 0;

  // if true, a maybeReadMore has been scheduled
  this.readingMore = false;

  this.decoder = null;
  this.encoding = null;
  if (options.encoding) {
    if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
    this.decoder = new StringDecoder(options.encoding);
    this.encoding = options.encoding;
  }
}

function Readable(options) {
  Duplex = Duplex || require('./_stream_duplex');

  if (!(this instanceof Readable)) return new Readable(options);

  this._readableState = new ReadableState(options, this);

  // legacy
  this.readable = true;

  if (options) {
    if (typeof options.read === 'function') this._read = options.read;

    if (typeof options.destroy === 'function') this._destroy = options.destroy;
  }

  Stream.call(this);
}

Object.defineProperty(Readable.prototype, 'destroyed', {
  get: function () {
    if (this._readableState === undefined) {
      return false;
    }
    return this._readableState.destroyed;
  },
  set: function (value) {
    // we ignore the value if the stream
    // has not been initialized yet
    if (!this._readableState) {
      return;
    }

    // backward compatibility, the user is explicitly
    // managing destroyed
    this._readableState.destroyed = value;
  }
});

Readable.prototype.destroy = destroyImpl.destroy;
Readable.prototype._undestroy = destroyImpl.undestroy;
Readable.prototype._destroy = function (err, cb) {
  this.push(null);
  cb(err);
};

// Manually shove something into the read() buffer.
// This returns true if the highWaterMark has not been hit yet,
// similar to how Writable.write() returns true if you should
// write() some more.
Readable.prototype.push = function (chunk, encoding) {
  var state = this._readableState;
  var skipChunkCheck;

  if (!state.objectMode) {
    if (typeof chunk === 'string') {
      encoding = encoding || state.defaultEncoding;
      if (encoding !== state.encoding) {
        chunk = Buffer.from(chunk, encoding);
        encoding = '';
      }
      skipChunkCheck = true;
    }
  } else {
    skipChunkCheck = true;
  }

  return readableAddChunk(this, chunk, encoding, false, skipChunkCheck);
};

// Unshift should *always* be something directly out of read()
Readable.prototype.unshift = function (chunk) {
  return readableAddChunk(this, chunk, null, true, false);
};

function readableAddChunk(stream, chunk, encoding, addToFront, skipChunkCheck) {
  var state = stream._readableState;
  if (chunk === null) {
    state.reading = false;
    onEofChunk(stream, state);
  } else {
    var er;
    if (!skipChunkCheck) er = chunkInvalid(state, chunk);
    if (er) {
      stream.emit('error', er);
    } else if (state.objectMode || chunk && chunk.length > 0) {
      if (typeof chunk !== 'string' && !state.objectMode && Object.getPrototypeOf(chunk) !== Buffer.prototype) {
        chunk = _uint8ArrayToBuffer(chunk);
      }

      if (addToFront) {
        if (state.endEmitted) stream.emit('error', new Error('stream.unshift() after end event'));else addChunk(stream, state, chunk, true);
      } else if (state.ended) {
        stream.emit('error', new Error('stream.push() after EOF'));
      } else {
        state.reading = false;
        if (state.decoder && !encoding) {
          chunk = state.decoder.write(chunk);
          if (state.objectMode || chunk.length !== 0) addChunk(stream, state, chunk, false);else maybeReadMore(stream, state);
        } else {
          addChunk(stream, state, chunk, false);
        }
      }
    } else if (!addToFront) {
      state.reading = false;
    }
  }

  return needMoreData(state);
}

function addChunk(stream, state, chunk, addToFront) {
  if (state.flowing && state.length === 0 && !state.sync) {
    stream.emit('data', chunk);
    stream.read(0);
  } else {
    // update the buffer info.
    state.length += state.objectMode ? 1 : chunk.length;
    if (addToFront) state.buffer.unshift(chunk);else state.buffer.push(chunk);

    if (state.needReadable) emitReadable(stream);
  }
  maybeReadMore(stream, state);
}

function chunkInvalid(state, chunk) {
  var er;
  if (!_isUint8Array(chunk) && typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
    er = new TypeError('Invalid non-string/buffer chunk');
  }
  return er;
}

// if it's past the high water mark, we can push in some more.
// Also, if we have no data yet, we can stand some
// more bytes.  This is to work around cases where hwm=0,
// such as the repl.  Also, if the push() triggered a
// readable event, and the user called read(largeNumber) such that
// needReadable was set, then we ought to push more, so that another
// 'readable' event will be triggered.
function needMoreData(state) {
  return !state.ended && (state.needReadable || state.length < state.highWaterMark || state.length === 0);
}

Readable.prototype.isPaused = function () {
  return this._readableState.flowing === false;
};

// backwards compatibility.
Readable.prototype.setEncoding = function (enc) {
  if (!StringDecoder) StringDecoder = require('string_decoder/').StringDecoder;
  this._readableState.decoder = new StringDecoder(enc);
  this._readableState.encoding = enc;
  return this;
};

// Don't raise the hwm > 8MB
var MAX_HWM = 0x800000;
function computeNewHighWaterMark(n) {
  if (n >= MAX_HWM) {
    n = MAX_HWM;
  } else {
    // Get the next highest power of 2 to prevent increasing hwm excessively in
    // tiny amounts
    n--;
    n |= n >>> 1;
    n |= n >>> 2;
    n |= n >>> 4;
    n |= n >>> 8;
    n |= n >>> 16;
    n++;
  }
  return n;
}

// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function howMuchToRead(n, state) {
  if (n <= 0 || state.length === 0 && state.ended) return 0;
  if (state.objectMode) return 1;
  if (n !== n) {
    // Only flow one buffer at a time
    if (state.flowing && state.length) return state.buffer.head.data.length;else return state.length;
  }
  // If we're asking for more than the current hwm, then raise the hwm.
  if (n > state.highWaterMark) state.highWaterMark = computeNewHighWaterMark(n);
  if (n <= state.length) return n;
  // Don't have enough
  if (!state.ended) {
    state.needReadable = true;
    return 0;
  }
  return state.length;
}

// you can override either this method, or the async _read(n) below.
Readable.prototype.read = function (n) {
  debug('read', n);
  n = parseInt(n, 10);
  var state = this._readableState;
  var nOrig = n;

  if (n !== 0) state.emittedReadable = false;

  // if we're doing read(0) to trigger a readable event, but we
  // already have a bunch of data in the buffer, then just trigger
  // the 'readable' event and move on.
  if (n === 0 && state.needReadable && (state.length >= state.highWaterMark || state.ended)) {
    debug('read: emitReadable', state.length, state.ended);
    if (state.length === 0 && state.ended) endReadable(this);else emitReadable(this);
    return null;
  }

  n = howMuchToRead(n, state);

  // if we've ended, and we're now clear, then finish it up.
  if (n === 0 && state.ended) {
    if (state.length === 0) endReadable(this);
    return null;
  }

  // All the actual chunk generation logic needs to be
  // *below* the call to _read.  The reason is that in certain
  // synthetic stream cases, such as passthrough streams, _read
  // may be a completely synchronous operation which may change
  // the state of the read buffer, providing enough data when
  // before there was *not* enough.
  //
  // So, the steps are:
  // 1. Figure out what the state of things will be after we do
  // a read from the buffer.
  //
  // 2. If that resulting state will trigger a _read, then call _read.
  // Note that this may be asynchronous, or synchronous.  Yes, it is
  // deeply ugly to write APIs this way, but that still doesn't mean
  // that the Readable class should behave improperly, as streams are
  // designed to be sync/async agnostic.
  // Take note if the _read call is sync or async (ie, if the read call
  // has returned yet), so that we know whether or not it's safe to emit
  // 'readable' etc.
  //
  // 3. Actually pull the requested chunks out of the buffer and return.

  // if we need a readable event, then we need to do some reading.
  var doRead = state.needReadable;
  debug('need readable', doRead);

  // if we currently have less than the highWaterMark, then also read some
  if (state.length === 0 || state.length - n < state.highWaterMark) {
    doRead = true;
    debug('length less than watermark', doRead);
  }

  // however, if we've ended, then there's no point, and if we're already
  // reading, then it's unnecessary.
  if (state.ended || state.reading) {
    doRead = false;
    debug('reading or ended', doRead);
  } else if (doRead) {
    debug('do read');
    state.reading = true;
    state.sync = true;
    // if the length is currently zero, then we *need* a readable event.
    if (state.length === 0) state.needReadable = true;
    // call internal read method
    this._read(state.highWaterMark);
    state.sync = false;
    // If _read pushed data synchronously, then `reading` will be false,
    // and we need to re-evaluate how much data we can return to the user.
    if (!state.reading) n = howMuchToRead(nOrig, state);
  }

  var ret;
  if (n > 0) ret = fromList(n, state);else ret = null;

  if (ret === null) {
    state.needReadable = true;
    n = 0;
  } else {
    state.length -= n;
  }

  if (state.length === 0) {
    // If we have nothing in the buffer, then we want to know
    // as soon as we *do* get something into the buffer.
    if (!state.ended) state.needReadable = true;

    // If we tried to read() past the EOF, then emit end on the next tick.
    if (nOrig !== n && state.ended) endReadable(this);
  }

  if (ret !== null) this.emit('data', ret);

  return ret;
};

function onEofChunk(stream, state) {
  if (state.ended) return;
  if (state.decoder) {
    var chunk = state.decoder.end();
    if (chunk && chunk.length) {
      state.buffer.push(chunk);
      state.length += state.objectMode ? 1 : chunk.length;
    }
  }
  state.ended = true;

  // emit 'readable' now to make sure it gets picked up.
  emitReadable(stream);
}

// Don't emit readable right away in sync mode, because this can trigger
// another read() call => stack overflow.  This way, it might trigger
// a nextTick recursion warning, but that's not so bad.
function emitReadable(stream) {
  var state = stream._readableState;
  state.needReadable = false;
  if (!state.emittedReadable) {
    debug('emitReadable', state.flowing);
    state.emittedReadable = true;
    if (state.sync) pna.nextTick(emitReadable_, stream);else emitReadable_(stream);
  }
}

function emitReadable_(stream) {
  debug('emit readable');
  stream.emit('readable');
  flow(stream);
}

// at this point, the user has presumably seen the 'readable' event,
// and called read() to consume some data.  that may have triggered
// in turn another _read(n) call, in which case reading = true if
// it's in progress.
// However, if we're not ended, or reading, and the length < hwm,
// then go ahead and try to read some more preemptively.
function maybeReadMore(stream, state) {
  if (!state.readingMore) {
    state.readingMore = true;
    pna.nextTick(maybeReadMore_, stream, state);
  }
}

function maybeReadMore_(stream, state) {
  var len = state.length;
  while (!state.reading && !state.flowing && !state.ended && state.length < state.highWaterMark) {
    debug('maybeReadMore read 0');
    stream.read(0);
    if (len === state.length)
      // didn't get any data, stop spinning.
      break;else len = state.length;
  }
  state.readingMore = false;
}

// abstract method.  to be overridden in specific implementation classes.
// call cb(er, data) where data is <= n in length.
// for virtual (non-string, non-buffer) streams, "length" is somewhat
// arbitrary, and perhaps not very meaningful.
Readable.prototype._read = function (n) {
  this.emit('error', new Error('_read() is not implemented'));
};

Readable.prototype.pipe = function (dest, pipeOpts) {
  var src = this;
  var state = this._readableState;

  switch (state.pipesCount) {
    case 0:
      state.pipes = dest;
      break;
    case 1:
      state.pipes = [state.pipes, dest];
      break;
    default:
      state.pipes.push(dest);
      break;
  }
  state.pipesCount += 1;
  debug('pipe count=%d opts=%j', state.pipesCount, pipeOpts);

  var doEnd = (!pipeOpts || pipeOpts.end !== false) && dest !== process.stdout && dest !== process.stderr;

  var endFn = doEnd ? onend : unpipe;
  if (state.endEmitted) pna.nextTick(endFn);else src.once('end', endFn);

  dest.on('unpipe', onunpipe);
  function onunpipe(readable, unpipeInfo) {
    debug('onunpipe');
    if (readable === src) {
      if (unpipeInfo && unpipeInfo.hasUnpiped === false) {
        unpipeInfo.hasUnpiped = true;
        cleanup();
      }
    }
  }

  function onend() {
    debug('onend');
    dest.end();
  }

  // when the dest drains, it reduces the awaitDrain counter
  // on the source.  This would be more elegant with a .once()
  // handler in flow(), but adding and removing repeatedly is
  // too slow.
  var ondrain = pipeOnDrain(src);
  dest.on('drain', ondrain);

  var cleanedUp = false;
  function cleanup() {
    debug('cleanup');
    // cleanup event handlers once the pipe is broken
    dest.removeListener('close', onclose);
    dest.removeListener('finish', onfinish);
    dest.removeListener('drain', ondrain);
    dest.removeListener('error', onerror);
    dest.removeListener('unpipe', onunpipe);
    src.removeListener('end', onend);
    src.removeListener('end', unpipe);
    src.removeListener('data', ondata);

    cleanedUp = true;

    // if the reader is waiting for a drain event from this
    // specific writer, then it would cause it to never start
    // flowing again.
    // So, if this is awaiting a drain, then we just call it now.
    // If we don't know, then assume that we are waiting for one.
    if (state.awaitDrain && (!dest._writableState || dest._writableState.needDrain)) ondrain();
  }

  // If the user pushes more data while we're writing to dest then we'll end up
  // in ondata again. However, we only want to increase awaitDrain once because
  // dest will only emit one 'drain' event for the multiple writes.
  // => Introduce a guard on increasing awaitDrain.
  var increasedAwaitDrain = false;
  src.on('data', ondata);
  function ondata(chunk) {
    debug('ondata');
    increasedAwaitDrain = false;
    var ret = dest.write(chunk);
    if (false === ret && !increasedAwaitDrain) {
      // If the user unpiped during `dest.write()`, it is possible
      // to get stuck in a permanently paused state if that write
      // also returned false.
      // => Check whether `dest` is still a piping destination.
      if ((state.pipesCount === 1 && state.pipes === dest || state.pipesCount > 1 && indexOf(state.pipes, dest) !== -1) && !cleanedUp) {
        debug('false write response, pause', src._readableState.awaitDrain);
        src._readableState.awaitDrain++;
        increasedAwaitDrain = true;
      }
      src.pause();
    }
  }

  // if the dest has an error, then stop piping into it.
  // however, don't suppress the throwing behavior for this.
  function onerror(er) {
    debug('onerror', er);
    unpipe();
    dest.removeListener('error', onerror);
    if (EElistenerCount(dest, 'error') === 0) dest.emit('error', er);
  }

  // Make sure our error handler is attached before userland ones.
  prependListener(dest, 'error', onerror);

  // Both close and finish should trigger unpipe, but only once.
  function onclose() {
    dest.removeListener('finish', onfinish);
    unpipe();
  }
  dest.once('close', onclose);
  function onfinish() {
    debug('onfinish');
    dest.removeListener('close', onclose);
    unpipe();
  }
  dest.once('finish', onfinish);

  function unpipe() {
    debug('unpipe');
    src.unpipe(dest);
  }

  // tell the dest that it's being piped to
  dest.emit('pipe', src);

  // start the flow if it hasn't been started already.
  if (!state.flowing) {
    debug('pipe resume');
    src.resume();
  }

  return dest;
};

function pipeOnDrain(src) {
  return function () {
    var state = src._readableState;
    debug('pipeOnDrain', state.awaitDrain);
    if (state.awaitDrain) state.awaitDrain--;
    if (state.awaitDrain === 0 && EElistenerCount(src, 'data')) {
      state.flowing = true;
      flow(src);
    }
  };
}

Readable.prototype.unpipe = function (dest) {
  var state = this._readableState;
  var unpipeInfo = { hasUnpiped: false };

  // if we're not piping anywhere, then do nothing.
  if (state.pipesCount === 0) return this;

  // just one destination.  most common case.
  if (state.pipesCount === 1) {
    // passed in one, but it's not the right one.
    if (dest && dest !== state.pipes) return this;

    if (!dest) dest = state.pipes;

    // got a match.
    state.pipes = null;
    state.pipesCount = 0;
    state.flowing = false;
    if (dest) dest.emit('unpipe', this, unpipeInfo);
    return this;
  }

  // slow case. multiple pipe destinations.

  if (!dest) {
    // remove all.
    var dests = state.pipes;
    var len = state.pipesCount;
    state.pipes = null;
    state.pipesCount = 0;
    state.flowing = false;

    for (var i = 0; i < len; i++) {
      dests[i].emit('unpipe', this, unpipeInfo);
    }return this;
  }

  // try to find the right one.
  var index = indexOf(state.pipes, dest);
  if (index === -1) return this;

  state.pipes.splice(index, 1);
  state.pipesCount -= 1;
  if (state.pipesCount === 1) state.pipes = state.pipes[0];

  dest.emit('unpipe', this, unpipeInfo);

  return this;
};

// set up data events if they are asked for
// Ensure readable listeners eventually get something
Readable.prototype.on = function (ev, fn) {
  var res = Stream.prototype.on.call(this, ev, fn);

  if (ev === 'data') {
    // Start flowing on next tick if stream isn't explicitly paused
    if (this._readableState.flowing !== false) this.resume();
  } else if (ev === 'readable') {
    var state = this._readableState;
    if (!state.endEmitted && !state.readableListening) {
      state.readableListening = state.needReadable = true;
      state.emittedReadable = false;
      if (!state.reading) {
        pna.nextTick(nReadingNextTick, this);
      } else if (state.length) {
        emitReadable(this);
      }
    }
  }

  return res;
};
Readable.prototype.addListener = Readable.prototype.on;

function nReadingNextTick(self) {
  debug('readable nexttick read 0');
  self.read(0);
}

// pause() and resume() are remnants of the legacy readable stream API
// If the user uses them, then switch into old mode.
Readable.prototype.resume = function () {
  var state = this._readableState;
  if (!state.flowing) {
    debug('resume');
    state.flowing = true;
    resume(this, state);
  }
  return this;
};

function resume(stream, state) {
  if (!state.resumeScheduled) {
    state.resumeScheduled = true;
    pna.nextTick(resume_, stream, state);
  }
}

function resume_(stream, state) {
  if (!state.reading) {
    debug('resume read 0');
    stream.read(0);
  }

  state.resumeScheduled = false;
  state.awaitDrain = 0;
  stream.emit('resume');
  flow(stream);
  if (state.flowing && !state.reading) stream.read(0);
}

Readable.prototype.pause = function () {
  debug('call pause flowing=%j', this._readableState.flowing);
  if (false !== this._readableState.flowing) {
    debug('pause');
    this._readableState.flowing = false;
    this.emit('pause');
  }
  return this;
};

function flow(stream) {
  var state = stream._readableState;
  debug('flow', state.flowing);
  while (state.flowing && stream.read() !== null) {}
}

// wrap an old-style stream as the async data source.
// This is *not* part of the readable stream interface.
// It is an ugly unfortunate mess of history.
Readable.prototype.wrap = function (stream) {
  var _this = this;

  var state = this._readableState;
  var paused = false;

  stream.on('end', function () {
    debug('wrapped end');
    if (state.decoder && !state.ended) {
      var chunk = state.decoder.end();
      if (chunk && chunk.length) _this.push(chunk);
    }

    _this.push(null);
  });

  stream.on('data', function (chunk) {
    debug('wrapped data');
    if (state.decoder) chunk = state.decoder.write(chunk);

    // don't skip over falsy values in objectMode
    if (state.objectMode && (chunk === null || chunk === undefined)) return;else if (!state.objectMode && (!chunk || !chunk.length)) return;

    var ret = _this.push(chunk);
    if (!ret) {
      paused = true;
      stream.pause();
    }
  });

  // proxy all the other methods.
  // important when wrapping filters and duplexes.
  for (var i in stream) {
    if (this[i] === undefined && typeof stream[i] === 'function') {
      this[i] = function (method) {
        return function () {
          return stream[method].apply(stream, arguments);
        };
      }(i);
    }
  }

  // proxy certain important events.
  for (var n = 0; n < kProxyEvents.length; n++) {
    stream.on(kProxyEvents[n], this.emit.bind(this, kProxyEvents[n]));
  }

  // when we try to consume some more bytes, simply unpause the
  // underlying stream.
  this._read = function (n) {
    debug('wrapped _read', n);
    if (paused) {
      paused = false;
      stream.resume();
    }
  };

  return this;
};

Object.defineProperty(Readable.prototype, 'readableHighWaterMark', {
  // making it explicit this property is not enumerable
  // because otherwise some prototype manipulation in
  // userland will fail
  enumerable: false,
  get: function () {
    return this._readableState.highWaterMark;
  }
});

// exposed for testing purposes only.
Readable._fromList = fromList;

// Pluck off n bytes from an array of buffers.
// Length is the combined lengths of all the buffers in the list.
// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function fromList(n, state) {
  // nothing buffered
  if (state.length === 0) return null;

  var ret;
  if (state.objectMode) ret = state.buffer.shift();else if (!n || n >= state.length) {
    // read it all, truncate the list
    if (state.decoder) ret = state.buffer.join('');else if (state.buffer.length === 1) ret = state.buffer.head.data;else ret = state.buffer.concat(state.length);
    state.buffer.clear();
  } else {
    // read part of list
    ret = fromListPartial(n, state.buffer, state.decoder);
  }

  return ret;
}

// Extracts only enough buffered data to satisfy the amount requested.
// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function fromListPartial(n, list, hasStrings) {
  var ret;
  if (n < list.head.data.length) {
    // slice is the same for buffers and strings
    ret = list.head.data.slice(0, n);
    list.head.data = list.head.data.slice(n);
  } else if (n === list.head.data.length) {
    // first chunk is a perfect match
    ret = list.shift();
  } else {
    // result spans more than one buffer
    ret = hasStrings ? copyFromBufferString(n, list) : copyFromBuffer(n, list);
  }
  return ret;
}

// Copies a specified amount of characters from the list of buffered data
// chunks.
// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function copyFromBufferString(n, list) {
  var p = list.head;
  var c = 1;
  var ret = p.data;
  n -= ret.length;
  while (p = p.next) {
    var str = p.data;
    var nb = n > str.length ? str.length : n;
    if (nb === str.length) ret += str;else ret += str.slice(0, n);
    n -= nb;
    if (n === 0) {
      if (nb === str.length) {
        ++c;
        if (p.next) list.head = p.next;else list.head = list.tail = null;
      } else {
        list.head = p;
        p.data = str.slice(nb);
      }
      break;
    }
    ++c;
  }
  list.length -= c;
  return ret;
}

// Copies a specified amount of bytes from the list of buffered data chunks.
// This function is designed to be inlinable, so please take care when making
// changes to the function body.
function copyFromBuffer(n, list) {
  var ret = Buffer.allocUnsafe(n);
  var p = list.head;
  var c = 1;
  p.data.copy(ret);
  n -= p.data.length;
  while (p = p.next) {
    var buf = p.data;
    var nb = n > buf.length ? buf.length : n;
    buf.copy(ret, ret.length - n, 0, nb);
    n -= nb;
    if (n === 0) {
      if (nb === buf.length) {
        ++c;
        if (p.next) list.head = p.next;else list.head = list.tail = null;
      } else {
        list.head = p;
        p.data = buf.slice(nb);
      }
      break;
    }
    ++c;
  }
  list.length -= c;
  return ret;
}

function endReadable(stream) {
  var state = stream._readableState;

  // If we get here before consuming all the bytes, then that is a
  // bug in node.  Should never happen.
  if (state.length > 0) throw new Error('"endReadable()" called on non-empty stream');

  if (!state.endEmitted) {
    state.ended = true;
    pna.nextTick(endReadableNT, state, stream);
  }
}

function endReadableNT(state, stream) {
  // Check that we didn't get one last unshift.
  if (!state.endEmitted && state.length === 0) {
    state.endEmitted = true;
    stream.readable = false;
    stream.emit('end');
  }
}

function indexOf(xs, x) {
  for (var i = 0, l = xs.length; i < l; i++) {
    if (xs[i] === x) return i;
  }
  return -1;
}
}).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
},{"./_stream_duplex":14,"./internal/streams/BufferList":19,"./internal/streams/destroy":20,"./internal/streams/stream":21,"_process":12,"core-util-is":4,"events":5,"inherits":8,"isarray":10,"process-nextick-args":11,"safe-buffer":23,"string_decoder/":28,"util":2}],17:[function(require,module,exports){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

// a transform stream is a readable/writable stream where you do
// something with the data.  Sometimes it's called a "filter",
// but that's not a great name for it, since that implies a thing where
// some bits pass through, and others are simply ignored.  (That would
// be a valid example of a transform, of course.)
//
// While the output is causally related to the input, it's not a
// necessarily symmetric or synchronous transformation.  For example,
// a zlib stream might take multiple plain-text writes(), and then
// emit a single compressed chunk some time in the future.
//
// Here's how this works:
//
// The Transform stream has all the aspects of the readable and writable
// stream classes.  When you write(chunk), that calls _write(chunk,cb)
// internally, and returns false if there's a lot of pending writes
// buffered up.  When you call read(), that calls _read(n) until
// there's enough pending readable data buffered up.
//
// In a transform stream, the written data is placed in a buffer.  When
// _read(n) is called, it transforms the queued up data, calling the
// buffered _write cb's as it consumes chunks.  If consuming a single
// written chunk would result in multiple output chunks, then the first
// outputted bit calls the readcb, and subsequent chunks just go into
// the read buffer, and will cause it to emit 'readable' if necessary.
//
// This way, back-pressure is actually determined by the reading side,
// since _read has to be called to start processing a new chunk.  However,
// a pathological inflate type of transform can cause excessive buffering
// here.  For example, imagine a stream where every byte of input is
// interpreted as an integer from 0-255, and then results in that many
// bytes of output.  Writing the 4 bytes {ff,ff,ff,ff} would result in
// 1kb of data being output.  In this case, you could write a very small
// amount of input, and end up with a very large amount of output.  In
// such a pathological inflating mechanism, there'd be no way to tell
// the system to stop doing the transform.  A single 4MB write could
// cause the system to run out of memory.
//
// However, even in such a pathological case, only a single written chunk
// would be consumed, and then the rest would wait (un-transformed) until
// the results of the previous transformed chunk were consumed.

'use strict';

module.exports = Transform;

var Duplex = require('./_stream_duplex');

/*<replacement>*/
var util = require('core-util-is');
util.inherits = require('inherits');
/*</replacement>*/

util.inherits(Transform, Duplex);

function afterTransform(er, data) {
  var ts = this._transformState;
  ts.transforming = false;

  var cb = ts.writecb;

  if (!cb) {
    return this.emit('error', new Error('write callback called multiple times'));
  }

  ts.writechunk = null;
  ts.writecb = null;

  if (data != null) // single equals check for both `null` and `undefined`
    this.push(data);

  cb(er);

  var rs = this._readableState;
  rs.reading = false;
  if (rs.needReadable || rs.length < rs.highWaterMark) {
    this._read(rs.highWaterMark);
  }
}

function Transform(options) {
  if (!(this instanceof Transform)) return new Transform(options);

  Duplex.call(this, options);

  this._transformState = {
    afterTransform: afterTransform.bind(this),
    needTransform: false,
    transforming: false,
    writecb: null,
    writechunk: null,
    writeencoding: null
  };

  // start out asking for a readable event once data is transformed.
  this._readableState.needReadable = true;

  // we have implemented the _read method, and done the other things
  // that Readable wants before the first _read call, so unset the
  // sync guard flag.
  this._readableState.sync = false;

  if (options) {
    if (typeof options.transform === 'function') this._transform = options.transform;

    if (typeof options.flush === 'function') this._flush = options.flush;
  }

  // When the writable side finishes, then flush out anything remaining.
  this.on('prefinish', prefinish);
}

function prefinish() {
  var _this = this;

  if (typeof this._flush === 'function') {
    this._flush(function (er, data) {
      done(_this, er, data);
    });
  } else {
    done(this, null, null);
  }
}

Transform.prototype.push = function (chunk, encoding) {
  this._transformState.needTransform = false;
  return Duplex.prototype.push.call(this, chunk, encoding);
};

// This is the part where you do stuff!
// override this function in implementation classes.
// 'chunk' is an input chunk.
//
// Call `push(newChunk)` to pass along transformed output
// to the readable side.  You may call 'push' zero or more times.
//
// Call `cb(err)` when you are done with this chunk.  If you pass
// an error, then that'll put the hurt on the whole operation.  If you
// never call cb(), then you'll never get another chunk.
Transform.prototype._transform = function (chunk, encoding, cb) {
  throw new Error('_transform() is not implemented');
};

Transform.prototype._write = function (chunk, encoding, cb) {
  var ts = this._transformState;
  ts.writecb = cb;
  ts.writechunk = chunk;
  ts.writeencoding = encoding;
  if (!ts.transforming) {
    var rs = this._readableState;
    if (ts.needTransform || rs.needReadable || rs.length < rs.highWaterMark) this._read(rs.highWaterMark);
  }
};

// Doesn't matter what the args are here.
// _transform does all the work.
// That we got here means that the readable side wants more data.
Transform.prototype._read = function (n) {
  var ts = this._transformState;

  if (ts.writechunk !== null && ts.writecb && !ts.transforming) {
    ts.transforming = true;
    this._transform(ts.writechunk, ts.writeencoding, ts.afterTransform);
  } else {
    // mark that we need a transform, so that any data that comes in
    // will get processed, now that we've asked for it.
    ts.needTransform = true;
  }
};

Transform.prototype._destroy = function (err, cb) {
  var _this2 = this;

  Duplex.prototype._destroy.call(this, err, function (err2) {
    cb(err2);
    _this2.emit('close');
  });
};

function done(stream, er, data) {
  if (er) return stream.emit('error', er);

  if (data != null) // single equals check for both `null` and `undefined`
    stream.push(data);

  // if there's nothing in the write buffer, then that means
  // that nothing more will ever be provided
  if (stream._writableState.length) throw new Error('Calling transform done when ws.length != 0');

  if (stream._transformState.transforming) throw new Error('Calling transform done when still transforming');

  return stream.push(null);
}
},{"./_stream_duplex":14,"core-util-is":4,"inherits":8}],18:[function(require,module,exports){
(function (process,global,setImmediate){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

// A bit simpler than readable streams.
// Implement an async ._write(chunk, encoding, cb), and it'll handle all
// the drain event emission and buffering.

'use strict';

/*<replacement>*/

var pna = require('process-nextick-args');
/*</replacement>*/

module.exports = Writable;

/* <replacement> */
function WriteReq(chunk, encoding, cb) {
  this.chunk = chunk;
  this.encoding = encoding;
  this.callback = cb;
  this.next = null;
}

// It seems a linked list but it is not
// there will be only 2 of these for each stream
function CorkedRequest(state) {
  var _this = this;

  this.next = null;
  this.entry = null;
  this.finish = function () {
    onCorkedFinish(_this, state);
  };
}
/* </replacement> */

/*<replacement>*/
var asyncWrite = !process.browser && ['v0.10', 'v0.9.'].indexOf(process.version.slice(0, 5)) > -1 ? setImmediate : pna.nextTick;
/*</replacement>*/

/*<replacement>*/
var Duplex;
/*</replacement>*/

Writable.WritableState = WritableState;

/*<replacement>*/
var util = require('core-util-is');
util.inherits = require('inherits');
/*</replacement>*/

/*<replacement>*/
var internalUtil = {
  deprecate: require('util-deprecate')
};
/*</replacement>*/

/*<replacement>*/
var Stream = require('./internal/streams/stream');
/*</replacement>*/

/*<replacement>*/

var Buffer = require('safe-buffer').Buffer;
var OurUint8Array = global.Uint8Array || function () {};
function _uint8ArrayToBuffer(chunk) {
  return Buffer.from(chunk);
}
function _isUint8Array(obj) {
  return Buffer.isBuffer(obj) || obj instanceof OurUint8Array;
}

/*</replacement>*/

var destroyImpl = require('./internal/streams/destroy');

util.inherits(Writable, Stream);

function nop() {}

function WritableState(options, stream) {
  Duplex = Duplex || require('./_stream_duplex');

  options = options || {};

  // Duplex streams are both readable and writable, but share
  // the same options object.
  // However, some cases require setting options to different
  // values for the readable and the writable sides of the duplex stream.
  // These options can be provided separately as readableXXX and writableXXX.
  var isDuplex = stream instanceof Duplex;

  // object stream flag to indicate whether or not this stream
  // contains buffers or objects.
  this.objectMode = !!options.objectMode;

  if (isDuplex) this.objectMode = this.objectMode || !!options.writableObjectMode;

  // the point at which write() starts returning false
  // Note: 0 is a valid value, means that we always return false if
  // the entire buffer is not flushed immediately on write()
  var hwm = options.highWaterMark;
  var writableHwm = options.writableHighWaterMark;
  var defaultHwm = this.objectMode ? 16 : 16 * 1024;

  if (hwm || hwm === 0) this.highWaterMark = hwm;else if (isDuplex && (writableHwm || writableHwm === 0)) this.highWaterMark = writableHwm;else this.highWaterMark = defaultHwm;

  // cast to ints.
  this.highWaterMark = Math.floor(this.highWaterMark);

  // if _final has been called
  this.finalCalled = false;

  // drain event flag.
  this.needDrain = false;
  // at the start of calling end()
  this.ending = false;
  // when end() has been called, and returned
  this.ended = false;
  // when 'finish' is emitted
  this.finished = false;

  // has it been destroyed
  this.destroyed = false;

  // should we decode strings into buffers before passing to _write?
  // this is here so that some node-core streams can optimize string
  // handling at a lower level.
  var noDecode = options.decodeStrings === false;
  this.decodeStrings = !noDecode;

  // Crypto is kind of old and crusty.  Historically, its default string
  // encoding is 'binary' so we have to make this configurable.
  // Everything else in the universe uses 'utf8', though.
  this.defaultEncoding = options.defaultEncoding || 'utf8';

  // not an actual buffer we keep track of, but a measurement
  // of how much we're waiting to get pushed to some underlying
  // socket or file.
  this.length = 0;

  // a flag to see when we're in the middle of a write.
  this.writing = false;

  // when true all writes will be buffered until .uncork() call
  this.corked = 0;

  // a flag to be able to tell if the onwrite cb is called immediately,
  // or on a later tick.  We set this to true at first, because any
  // actions that shouldn't happen until "later" should generally also
  // not happen before the first write call.
  this.sync = true;

  // a flag to know if we're processing previously buffered items, which
  // may call the _write() callback in the same tick, so that we don't
  // end up in an overlapped onwrite situation.
  this.bufferProcessing = false;

  // the callback that's passed to _write(chunk,cb)
  this.onwrite = function (er) {
    onwrite(stream, er);
  };

  // the callback that the user supplies to write(chunk,encoding,cb)
  this.writecb = null;

  // the amount that is being written when _write is called.
  this.writelen = 0;

  this.bufferedRequest = null;
  this.lastBufferedRequest = null;

  // number of pending user-supplied write callbacks
  // this must be 0 before 'finish' can be emitted
  this.pendingcb = 0;

  // emit prefinish if the only thing we're waiting for is _write cbs
  // This is relevant for synchronous Transform streams
  this.prefinished = false;

  // True if the error was already emitted and should not be thrown again
  this.errorEmitted = false;

  // count buffered requests
  this.bufferedRequestCount = 0;

  // allocate the first CorkedRequest, there is always
  // one allocated and free to use, and we maintain at most two
  this.corkedRequestsFree = new CorkedRequest(this);
}

WritableState.prototype.getBuffer = function getBuffer() {
  var current = this.bufferedRequest;
  var out = [];
  while (current) {
    out.push(current);
    current = current.next;
  }
  return out;
};

(function () {
  try {
    Object.defineProperty(WritableState.prototype, 'buffer', {
      get: internalUtil.deprecate(function () {
        return this.getBuffer();
      }, '_writableState.buffer is deprecated. Use _writableState.getBuffer ' + 'instead.', 'DEP0003')
    });
  } catch (_) {}
})();

// Test _writableState for inheritance to account for Duplex streams,
// whose prototype chain only points to Readable.
var realHasInstance;
if (typeof Symbol === 'function' && Symbol.hasInstance && typeof Function.prototype[Symbol.hasInstance] === 'function') {
  realHasInstance = Function.prototype[Symbol.hasInstance];
  Object.defineProperty(Writable, Symbol.hasInstance, {
    value: function (object) {
      if (realHasInstance.call(this, object)) return true;
      if (this !== Writable) return false;

      return object && object._writableState instanceof WritableState;
    }
  });
} else {
  realHasInstance = function (object) {
    return object instanceof this;
  };
}

function Writable(options) {
  Duplex = Duplex || require('./_stream_duplex');

  // Writable ctor is applied to Duplexes, too.
  // `realHasInstance` is necessary because using plain `instanceof`
  // would return false, as no `_writableState` property is attached.

  // Trying to use the custom `instanceof` for Writable here will also break the
  // Node.js LazyTransform implementation, which has a non-trivial getter for
  // `_writableState` that would lead to infinite recursion.
  if (!realHasInstance.call(Writable, this) && !(this instanceof Duplex)) {
    return new Writable(options);
  }

  this._writableState = new WritableState(options, this);

  // legacy.
  this.writable = true;

  if (options) {
    if (typeof options.write === 'function') this._write = options.write;

    if (typeof options.writev === 'function') this._writev = options.writev;

    if (typeof options.destroy === 'function') this._destroy = options.destroy;

    if (typeof options.final === 'function') this._final = options.final;
  }

  Stream.call(this);
}

// Otherwise people can pipe Writable streams, which is just wrong.
Writable.prototype.pipe = function () {
  this.emit('error', new Error('Cannot pipe, not readable'));
};

function writeAfterEnd(stream, cb) {
  var er = new Error('write after end');
  // TODO: defer error events consistently everywhere, not just the cb
  stream.emit('error', er);
  pna.nextTick(cb, er);
}

// Checks that a user-supplied chunk is valid, especially for the particular
// mode the stream is in. Currently this means that `null` is never accepted
// and undefined/non-string values are only allowed in object mode.
function validChunk(stream, state, chunk, cb) {
  var valid = true;
  var er = false;

  if (chunk === null) {
    er = new TypeError('May not write null values to stream');
  } else if (typeof chunk !== 'string' && chunk !== undefined && !state.objectMode) {
    er = new TypeError('Invalid non-string/buffer chunk');
  }
  if (er) {
    stream.emit('error', er);
    pna.nextTick(cb, er);
    valid = false;
  }
  return valid;
}

Writable.prototype.write = function (chunk, encoding, cb) {
  var state = this._writableState;
  var ret = false;
  var isBuf = !state.objectMode && _isUint8Array(chunk);

  if (isBuf && !Buffer.isBuffer(chunk)) {
    chunk = _uint8ArrayToBuffer(chunk);
  }

  if (typeof encoding === 'function') {
    cb = encoding;
    encoding = null;
  }

  if (isBuf) encoding = 'buffer';else if (!encoding) encoding = state.defaultEncoding;

  if (typeof cb !== 'function') cb = nop;

  if (state.ended) writeAfterEnd(this, cb);else if (isBuf || validChunk(this, state, chunk, cb)) {
    state.pendingcb++;
    ret = writeOrBuffer(this, state, isBuf, chunk, encoding, cb);
  }

  return ret;
};

Writable.prototype.cork = function () {
  var state = this._writableState;

  state.corked++;
};

Writable.prototype.uncork = function () {
  var state = this._writableState;

  if (state.corked) {
    state.corked--;

    if (!state.writing && !state.corked && !state.finished && !state.bufferProcessing && state.bufferedRequest) clearBuffer(this, state);
  }
};

Writable.prototype.setDefaultEncoding = function setDefaultEncoding(encoding) {
  // node::ParseEncoding() requires lower case.
  if (typeof encoding === 'string') encoding = encoding.toLowerCase();
  if (!(['hex', 'utf8', 'utf-8', 'ascii', 'binary', 'base64', 'ucs2', 'ucs-2', 'utf16le', 'utf-16le', 'raw'].indexOf((encoding + '').toLowerCase()) > -1)) throw new TypeError('Unknown encoding: ' + encoding);
  this._writableState.defaultEncoding = encoding;
  return this;
};

function decodeChunk(state, chunk, encoding) {
  if (!state.objectMode && state.decodeStrings !== false && typeof chunk === 'string') {
    chunk = Buffer.from(chunk, encoding);
  }
  return chunk;
}

Object.defineProperty(Writable.prototype, 'writableHighWaterMark', {
  // making it explicit this property is not enumerable
  // because otherwise some prototype manipulation in
  // userland will fail
  enumerable: false,
  get: function () {
    return this._writableState.highWaterMark;
  }
});

// if we're already writing something, then just put this
// in the queue, and wait our turn.  Otherwise, call _write
// If we return false, then we need a drain event, so set that flag.
function writeOrBuffer(stream, state, isBuf, chunk, encoding, cb) {
  if (!isBuf) {
    var newChunk = decodeChunk(state, chunk, encoding);
    if (chunk !== newChunk) {
      isBuf = true;
      encoding = 'buffer';
      chunk = newChunk;
    }
  }
  var len = state.objectMode ? 1 : chunk.length;

  state.length += len;

  var ret = state.length < state.highWaterMark;
  // we must ensure that previous needDrain will not be reset to false.
  if (!ret) state.needDrain = true;

  if (state.writing || state.corked) {
    var last = state.lastBufferedRequest;
    state.lastBufferedRequest = {
      chunk: chunk,
      encoding: encoding,
      isBuf: isBuf,
      callback: cb,
      next: null
    };
    if (last) {
      last.next = state.lastBufferedRequest;
    } else {
      state.bufferedRequest = state.lastBufferedRequest;
    }
    state.bufferedRequestCount += 1;
  } else {
    doWrite(stream, state, false, len, chunk, encoding, cb);
  }

  return ret;
}

function doWrite(stream, state, writev, len, chunk, encoding, cb) {
  state.writelen = len;
  state.writecb = cb;
  state.writing = true;
  state.sync = true;
  if (writev) stream._writev(chunk, state.onwrite);else stream._write(chunk, encoding, state.onwrite);
  state.sync = false;
}

function onwriteError(stream, state, sync, er, cb) {
  --state.pendingcb;

  if (sync) {
    // defer the callback if we are being called synchronously
    // to avoid piling up things on the stack
    pna.nextTick(cb, er);
    // this can emit finish, and it will always happen
    // after error
    pna.nextTick(finishMaybe, stream, state);
    stream._writableState.errorEmitted = true;
    stream.emit('error', er);
  } else {
    // the caller expect this to happen before if
    // it is async
    cb(er);
    stream._writableState.errorEmitted = true;
    stream.emit('error', er);
    // this can emit finish, but finish must
    // always follow error
    finishMaybe(stream, state);
  }
}

function onwriteStateUpdate(state) {
  state.writing = false;
  state.writecb = null;
  state.length -= state.writelen;
  state.writelen = 0;
}

function onwrite(stream, er) {
  var state = stream._writableState;
  var sync = state.sync;
  var cb = state.writecb;

  onwriteStateUpdate(state);

  if (er) onwriteError(stream, state, sync, er, cb);else {
    // Check if we're actually ready to finish, but don't emit yet
    var finished = needFinish(state);

    if (!finished && !state.corked && !state.bufferProcessing && state.bufferedRequest) {
      clearBuffer(stream, state);
    }

    if (sync) {
      /*<replacement>*/
      asyncWrite(afterWrite, stream, state, finished, cb);
      /*</replacement>*/
    } else {
      afterWrite(stream, state, finished, cb);
    }
  }
}

function afterWrite(stream, state, finished, cb) {
  if (!finished) onwriteDrain(stream, state);
  state.pendingcb--;
  cb();
  finishMaybe(stream, state);
}

// Must force callback to be called on nextTick, so that we don't
// emit 'drain' before the write() consumer gets the 'false' return
// value, and has a chance to attach a 'drain' listener.
function onwriteDrain(stream, state) {
  if (state.length === 0 && state.needDrain) {
    state.needDrain = false;
    stream.emit('drain');
  }
}

// if there's something in the buffer waiting, then process it
function clearBuffer(stream, state) {
  state.bufferProcessing = true;
  var entry = state.bufferedRequest;

  if (stream._writev && entry && entry.next) {
    // Fast case, write everything using _writev()
    var l = state.bufferedRequestCount;
    var buffer = new Array(l);
    var holder = state.corkedRequestsFree;
    holder.entry = entry;

    var count = 0;
    var allBuffers = true;
    while (entry) {
      buffer[count] = entry;
      if (!entry.isBuf) allBuffers = false;
      entry = entry.next;
      count += 1;
    }
    buffer.allBuffers = allBuffers;

    doWrite(stream, state, true, state.length, buffer, '', holder.finish);

    // doWrite is almost always async, defer these to save a bit of time
    // as the hot path ends with doWrite
    state.pendingcb++;
    state.lastBufferedRequest = null;
    if (holder.next) {
      state.corkedRequestsFree = holder.next;
      holder.next = null;
    } else {
      state.corkedRequestsFree = new CorkedRequest(state);
    }
    state.bufferedRequestCount = 0;
  } else {
    // Slow case, write chunks one-by-one
    while (entry) {
      var chunk = entry.chunk;
      var encoding = entry.encoding;
      var cb = entry.callback;
      var len = state.objectMode ? 1 : chunk.length;

      doWrite(stream, state, false, len, chunk, encoding, cb);
      entry = entry.next;
      state.bufferedRequestCount--;
      // if we didn't call the onwrite immediately, then
      // it means that we need to wait until it does.
      // also, that means that the chunk and cb are currently
      // being processed, so move the buffer counter past them.
      if (state.writing) {
        break;
      }
    }

    if (entry === null) state.lastBufferedRequest = null;
  }

  state.bufferedRequest = entry;
  state.bufferProcessing = false;
}

Writable.prototype._write = function (chunk, encoding, cb) {
  cb(new Error('_write() is not implemented'));
};

Writable.prototype._writev = null;

Writable.prototype.end = function (chunk, encoding, cb) {
  var state = this._writableState;

  if (typeof chunk === 'function') {
    cb = chunk;
    chunk = null;
    encoding = null;
  } else if (typeof encoding === 'function') {
    cb = encoding;
    encoding = null;
  }

  if (chunk !== null && chunk !== undefined) this.write(chunk, encoding);

  // .end() fully uncorks
  if (state.corked) {
    state.corked = 1;
    this.uncork();
  }

  // ignore unnecessary end() calls.
  if (!state.ending && !state.finished) endWritable(this, state, cb);
};

function needFinish(state) {
  return state.ending && state.length === 0 && state.bufferedRequest === null && !state.finished && !state.writing;
}
function callFinal(stream, state) {
  stream._final(function (err) {
    state.pendingcb--;
    if (err) {
      stream.emit('error', err);
    }
    state.prefinished = true;
    stream.emit('prefinish');
    finishMaybe(stream, state);
  });
}
function prefinish(stream, state) {
  if (!state.prefinished && !state.finalCalled) {
    if (typeof stream._final === 'function') {
      state.pendingcb++;
      state.finalCalled = true;
      pna.nextTick(callFinal, stream, state);
    } else {
      state.prefinished = true;
      stream.emit('prefinish');
    }
  }
}

function finishMaybe(stream, state) {
  var need = needFinish(state);
  if (need) {
    prefinish(stream, state);
    if (state.pendingcb === 0) {
      state.finished = true;
      stream.emit('finish');
    }
  }
  return need;
}

function endWritable(stream, state, cb) {
  state.ending = true;
  finishMaybe(stream, state);
  if (cb) {
    if (state.finished) pna.nextTick(cb);else stream.once('finish', cb);
  }
  state.ended = true;
  stream.writable = false;
}

function onCorkedFinish(corkReq, state, err) {
  var entry = corkReq.entry;
  corkReq.entry = null;
  while (entry) {
    var cb = entry.callback;
    state.pendingcb--;
    cb(err);
    entry = entry.next;
  }
  if (state.corkedRequestsFree) {
    state.corkedRequestsFree.next = corkReq;
  } else {
    state.corkedRequestsFree = corkReq;
  }
}

Object.defineProperty(Writable.prototype, 'destroyed', {
  get: function () {
    if (this._writableState === undefined) {
      return false;
    }
    return this._writableState.destroyed;
  },
  set: function (value) {
    // we ignore the value if the stream
    // has not been initialized yet
    if (!this._writableState) {
      return;
    }

    // backward compatibility, the user is explicitly
    // managing destroyed
    this._writableState.destroyed = value;
  }
});

Writable.prototype.destroy = destroyImpl.destroy;
Writable.prototype._undestroy = destroyImpl.undestroy;
Writable.prototype._destroy = function (err, cb) {
  this.end();
  cb(err);
};
}).call(this,require('_process'),typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {},require("timers").setImmediate)
},{"./_stream_duplex":14,"./internal/streams/destroy":20,"./internal/streams/stream":21,"_process":12,"core-util-is":4,"inherits":8,"process-nextick-args":11,"safe-buffer":23,"timers":29,"util-deprecate":30}],19:[function(require,module,exports){
'use strict';

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Buffer = require('safe-buffer').Buffer;
var util = require('util');

function copyBuffer(src, target, offset) {
  src.copy(target, offset);
}

module.exports = function () {
  function BufferList() {
    _classCallCheck(this, BufferList);

    this.head = null;
    this.tail = null;
    this.length = 0;
  }

  BufferList.prototype.push = function push(v) {
    var entry = { data: v, next: null };
    if (this.length > 0) this.tail.next = entry;else this.head = entry;
    this.tail = entry;
    ++this.length;
  };

  BufferList.prototype.unshift = function unshift(v) {
    var entry = { data: v, next: this.head };
    if (this.length === 0) this.tail = entry;
    this.head = entry;
    ++this.length;
  };

  BufferList.prototype.shift = function shift() {
    if (this.length === 0) return;
    var ret = this.head.data;
    if (this.length === 1) this.head = this.tail = null;else this.head = this.head.next;
    --this.length;
    return ret;
  };

  BufferList.prototype.clear = function clear() {
    this.head = this.tail = null;
    this.length = 0;
  };

  BufferList.prototype.join = function join(s) {
    if (this.length === 0) return '';
    var p = this.head;
    var ret="" + p.data;
    while (p = p.next) {
      ret += s + p.data;
    }return ret;
  };

  BufferList.prototype.concat = function concat(n) {
    if (this.length === 0) return Buffer.alloc(0);
    if (this.length === 1) return this.head.data;
    var ret = Buffer.allocUnsafe(n >>> 0);
    var p = this.head;
    var i = 0;
    while (p) {
      copyBuffer(p.data, ret, i);
      i += p.data.length;
      p = p.next;
    }
    return ret;
  };

  return BufferList;
}();

if (util && util.inspect && util.inspect.custom) {
  module.exports.prototype[util.inspect.custom] = function () {
    var obj = util.inspect({ length: this.length });
    return this.constructor.name + ' ' + obj;
  };
}
},{"safe-buffer":23,"util":2}],20:[function(require,module,exports){
'use strict';

/*<replacement>*/

var pna = require('process-nextick-args');
/*</replacement>*/

// undocumented cb() API, needed for core, not for public API
function destroy(err, cb) {
  var _this = this;

  var readableDestroyed = this._readableState && this._readableState.destroyed;
  var writableDestroyed = this._writableState && this._writableState.destroyed;

  if (readableDestroyed || writableDestroyed) {
    if (cb) {
      cb(err);
    } else if (err && (!this._writableState || !this._writableState.errorEmitted)) {
      pna.nextTick(emitErrorNT, this, err);
    }
    return this;
  }

  // we set destroyed to true before firing error callbacks in order
  // to make it re-entrance safe in case destroy() is called within callbacks

  if (this._readableState) {
    this._readableState.destroyed = true;
  }

  // if this is a duplex stream mark the writable part as destroyed as well
  if (this._writableState) {
    this._writableState.destroyed = true;
  }

  this._destroy(err || null, function (err) {
    if (!cb && err) {
      pna.nextTick(emitErrorNT, _this, err);
      if (_this._writableState) {
        _this._writableState.errorEmitted = true;
      }
    } else if (cb) {
      cb(err);
    }
  });

  return this;
}

function undestroy() {
  if (this._readableState) {
    this._readableState.destroyed = false;
    this._readableState.reading = false;
    this._readableState.ended = false;
    this._readableState.endEmitted = false;
  }

  if (this._writableState) {
    this._writableState.destroyed = false;
    this._writableState.ended = false;
    this._writableState.ending = false;
    this._writableState.finished = false;
    this._writableState.errorEmitted = false;
  }
}

function emitErrorNT(self, err) {
  self.emit('error', err);
}

module.exports = {
  destroy: destroy,
  undestroy: undestroy
};
},{"process-nextick-args":11}],21:[function(require,module,exports){
module.exports = require('events').EventEmitter;

},{"events":5}],22:[function(require,module,exports){
exports = module.exports = require('./lib/_stream_readable.js');
exports.Stream = exports;
exports.Readable = exports;
exports.Writable = require('./lib/_stream_writable.js');
exports.Duplex = require('./lib/_stream_duplex.js');
exports.Transform = require('./lib/_stream_transform.js');
exports.PassThrough = require('./lib/_stream_passthrough.js');

},{"./lib/_stream_duplex.js":14,"./lib/_stream_passthrough.js":15,"./lib/_stream_readable.js":16,"./lib/_stream_transform.js":17,"./lib/_stream_writable.js":18}],23:[function(require,module,exports){
/* eslint-disable node/no-deprecated-api */
var buffer = require('buffer')
var Buffer = buffer.Buffer

// alternative to using Object.keys for old browsers
function copyProps (src, dst) {
  for (var key in src) {
    dst[key] = src[key]
  }
}
if (Buffer.from && Buffer.alloc && Buffer.allocUnsafe && Buffer.allocUnsafeSlow) {
  module.exports = buffer
} else {
  // Copy properties from require('buffer')
  copyProps(buffer, exports)
  exports.Buffer = SafeBuffer
}

function SafeBuffer (arg, encodingOrOffset, length) {
  return Buffer(arg, encodingOrOffset, length)
}

// Copy static methods from Buffer
copyProps(Buffer, SafeBuffer)

SafeBuffer.from = function (arg, encodingOrOffset, length) {
  if (typeof arg === 'number') {
    throw new TypeError('Argument must not be a number')
  }
  return Buffer(arg, encodingOrOffset, length)
}

SafeBuffer.alloc = function (size, fill, encoding) {
  if (typeof size !== 'number') {
    throw new TypeError('Argument must be a number')
  }
  var buf = Buffer(size)
  if (fill !== undefined) {
    if (typeof encoding === 'string') {
      buf.fill(fill, encoding)
    } else {
      buf.fill(fill)
    }
  } else {
    buf.fill(0)
  }
  return buf
}

SafeBuffer.allocUnsafe = function (size) {
  if (typeof size !== 'number') {
    throw new TypeError('Argument must be a number')
  }
  return Buffer(size)
}

SafeBuffer.allocUnsafeSlow = function (size) {
  if (typeof size !== 'number') {
    throw new TypeError('Argument must be a number')
  }
  return buffer.SlowBuffer(size)
}

},{"buffer":3}],24:[function(require,module,exports){
(function (Buffer){
module.exports = Peer

var debug = require('debug')('simple-peer')
var getBrowserRTC = require('get-browser-rtc')
var inherits = require('inherits')
var randombytes = require('randombytes')
var stream = require('readable-stream')

var MAX_BUFFERED_AMOUNT = 64 * 1024
var ICECOMPLETE_TIMEOUT = 5 * 1000
var CHANNEL_CLOSING_TIMEOUT = 5 * 1000

inherits(Peer, stream.Duplex)

/**
 * WebRTC peer connection. Same API as node core `net.Socket`, plus a few extra methods.
 * Duplex stream.
 * @param {Object} opts
 */
function Peer (opts) {
  var self = this
  if (!(self instanceof Peer)) return new Peer(opts)

  self._id = randombytes(4).toString('hex').slice(0, 7)
  self._debug('new peer %o', opts)

  opts = Object.assign({
    allowHalfOpen: false
  }, opts)

  stream.Duplex.call(self, opts)

  self.channelName = opts.initiator
    ? opts.channelName || randombytes(20).toString('hex')
    : null

  self.initiator = opts.initiator || false
  self.channelConfig = opts.channelConfig || Peer.channelConfig
  self.config = Object.assign({}, Peer.config, opts.config)
  self.offerOptions = opts.offerOptions || {}
  self.answerOptions = opts.answerOptions || {}
  self.sdpTransform = opts.sdpTransform || function (sdp) { return sdp }
  self.streams = opts.streams || (opts.stream ? [opts.stream] : []) // support old "stream" option
  self.trickle = opts.trickle !== undefined ? opts.trickle : true
  self.allowHalfTrickle = opts.allowHalfTrickle !== undefined ? opts.allowHalfTrickle : false
  self.iceCompleteTimeout = opts.iceCompleteTimeout || ICECOMPLETE_TIMEOUT

  self.destroyed = false
  self.connected = false

  self.remoteAddress = undefined
  self.remoteFamily = undefined
  self.remotePort = undefined
  self.localAddress = undefined
  self.localFamily = undefined
  self.localPort = undefined

  self._wrtc = (opts.wrtc && typeof opts.wrtc === 'object')
    ? opts.wrtc
    : getBrowserRTC()

  if (!self._wrtc) {
    if (typeof window === 'undefined') {
      throw makeError('No WebRTC support: Specify `opts.wrtc` option in this environment', 'ERR_WEBRTC_SUPPORT')
    } else {
      throw makeError('No WebRTC support: Not a supported browser', 'ERR_WEBRTC_SUPPORT')
    }
  }

  self._pcReady = false
  self._channelReady = false
  self._iceComplete = false // ice candidate trickle done (got null candidate)
  self._iceCompleteTimer = null // send an offer/answer anyway after some timeout
  self._channel = null
  self._pendingCandidates = []

  self._isNegotiating = !self.initiator // is this peer waiting for negotiation to complete?
  self._batchedNegotiation = false // batch synchronous negotiations
  self._queuedNegotiation = false // is there a queued negotiation request?
  self._sendersAwaitingStable = []
  self._senderMap = new Map()
  self._firstStable = true
  self._closingInterval = null

  self._remoteTracks = []
  self._remoteStreams = []

  self._chunk = null
  self._cb = null
  self._interval = null

  try {
    self._pc = new (self._wrtc.RTCPeerConnection)(self.config)
  } catch (err) {
    self.destroy(err)
  }

  // We prefer feature detection whenever possible, but sometimes that's not
  // possible for certain implementations.
  self._isReactNativeWebrtc = typeof self._pc._peerConnectionId === 'number'

  self._pc.oniceconnectionstatechange = function () {
    self._onIceStateChange()
  }
  self._pc.onicegatheringstatechange = function () {
    self._onIceStateChange()
  }
  self._pc.onsignalingstatechange = function () {
    self._onSignalingStateChange()
  }
  self._pc.onicecandidate = function (event) {
    self._onIceCandidate(event)
  }

  // Other spec events, unused by this implementation:
  // - onconnectionstatechange
  // - onicecandidateerror
  // - onfingerprintfailure
  // - onnegotiationneeded

  if (self.initiator) {
    self._setupData({
      channel: self._pc.createDataChannel(self.channelName, self.channelConfig)
    })
  } else {
    self._pc.ondatachannel = function (event) {
      self._setupData(event)
    }
  }

  if (self.streams) {
    self.streams.forEach(function (stream) {
      self.addStream(stream)
    })
  }
  self._pc.ontrack = function (event) {
    self._onTrack(event)
  }

  if (self.initiator) {
    self._needsNegotiation()
  }

  self._onFinishBound = function () {
    self._onFinish()
  }
  self.once('finish', self._onFinishBound)
}

Peer.WEBRTC_SUPPORT = !!getBrowserRTC()

/**
 * Expose peer and data channel config for overriding all Peer
 * instances. Otherwise, just set opts.config or opts.channelConfig
 * when constructing a Peer.
 */
Peer.config = {
  iceServers: [
    {
      urls: 'stun:stun.l.google.com:19302'
    },
    {
      urls: 'stun:global.stun.twilio.com:3478?transport=udp'
    }
  ],
  sdpSemantics: 'unified-plan'
}
Peer.channelConfig = {}

Object.defineProperty(Peer.prototype, 'bufferSize', {
  get: function () {
    var self = this
    return (self._channel && self._channel.bufferedAmount) || 0
  }
})

Peer.prototype.address = function () {
  var self = this
  return { port: self.localPort, family: self.localFamily, address: self.localAddress }
}

Peer.prototype.signal = function (data) {
  var self = this
  if (self.destroyed) throw makeError('cannot signal after peer is destroyed', 'ERR_SIGNALING')
  if (typeof data === 'string') {
    try {
      data = JSON.parse(data)
    } catch (err) {
      data = {}
    }
  }
  self._debug('signal()')

  if (data.renegotiate && self.initiator) {
    self._debug('got request to renegotiate')
    self._needsNegotiation()
  }
  if (data.transceiverRequest && self.initiator) {
    self._debug('got request for transceiver')
    self.addTransceiver(data.transceiverRequest.kind, data.transceiverRequest.init)
  }
  if (data.candidate) {
    if (self._pc.localDescription && self._pc.localDescription.type && self._pc.remoteDescription && self._pc.remoteDescription.type) {
      self._addIceCandidate(data.candidate)
    } else {
      self._pendingCandidates.push(data.candidate)
    }
  }
  if (data.sdp) {
    self._pc.setRemoteDescription(new (self._wrtc.RTCSessionDescription)(data)).then(function () {
      if (self.destroyed) return

      self._pendingCandidates.forEach(function (candidate) {
        self._addIceCandidate(candidate)
      })
      self._pendingCandidates = []

      if (self._pc.remoteDescription.type === 'offer') self._createAnswer()
    }).catch(function (err) { self.destroy(makeError(err, 'ERR_SET_REMOTE_DESCRIPTION')) })
  }
  if (!data.sdp && !data.candidate && !data.renegotiate && !data.transceiverRequest) {
    self.destroy(makeError('signal() called with invalid signal data', 'ERR_SIGNALING'))
  }
}

Peer.prototype._addIceCandidate = function (candidate) {
  var self = this
  self._pc.addIceCandidate(new self._wrtc.RTCIceCandidate(candidate)).catch(function (err) {
    // HACK: node-webrtc throws an incorrect error https://github.com/node-webrtc/node-webrtc/issues/498
    if (self._pc.signalingState !== 'closed' && err.message === 'Failed to set ICE candidate; RTCPeerConnection is closed.') {
      return self._debug('ignoring incorrect wrtc error')
    }
    self.destroy(makeError(err, 'ERR_ADD_ICE_CANDIDATE'))
  })
}

/**
 * Send text/binary data to the remote peer.
 * @param {ArrayBufferView|ArrayBuffer|Buffer|string|Blob} chunk
 */
Peer.prototype.send = function (chunk) {
  var self = this
  self._channel.send(chunk)
}

/**
 * Add a Transceiver to the connection.
 * @param {String} kind
 * @param {Object} init
 */
Peer.prototype.addTransceiver = function (kind, init) {
  var self = this

  self._debug('addTransceiver()')

  if (self.initiator) {
    try {
      self._pc.addTransceiver(kind, init)
      self._needsNegotiation()
    } catch (err) {
      self.destroy(err)
    }
  } else {
    self.emit('signal', { // request initiator to renegotiate
      transceiverRequest: { kind, init }
    })
  }
}

/**
 * Add a MediaStream to the connection.
 * @param {MediaStream} stream
 */
Peer.prototype.addStream = function (stream) {
  var self = this

  self._debug('addStream()')

  stream.getTracks().forEach(function (track) {
    self.addTrack(track, stream)
  })
}

/**
 * Add a MediaStreamTrack to the connection.
 * @param {MediaStreamTrack} track
 * @param {MediaStream} stream
 */
Peer.prototype.addTrack = function (track, stream) {
  var self = this

  self._debug('addTrack()')

  var submap = self._senderMap.get(track) || new Map() // nested Maps map [track, stream] to sender
  var sender = submap.get(stream)
  if (!sender) {
    sender = self._pc.addTrack(track, stream)
    submap.set(stream, sender)
    self._senderMap.set(track, submap)
    self._needsNegotiation()
  } else if (sender.removed) {
    self.destroy(makeError('Track has been removed. You should enable/disable tracks that you want to re-add.'), 'ERR_SENDER_REMOVED')
  } else {
    self.destroy(makeError('Track has already been added to that stream.'), 'ERR_SENDER_ALREADY_ADDED')
  }
}

/**
 * Replace a MediaStreamTrack by another in the connection.
 * @param {MediaStreamTrack} oldTrack
 * @param {MediaStreamTrack} newTrack
 * @param {MediaStream} stream
 */
Peer.prototype.replaceTrack = function (oldTrack, newTrack, stream) {
  var self = this

  self._debug('replaceTrack()')

  var submap = self._senderMap.get(oldTrack)
  var sender = submap ? submap.get(stream) : null
  if (!sender) {
    self.destroy(makeError('Cannot replace track that was never added.'), 'ERR_TRACK_NOT_ADDED')
  }
  if (newTrack) self._senderMap.set(newTrack, submap)

  if (sender.replaceTrack != null) {
    sender.replaceTrack(newTrack)
  } else {
    self.destroy(makeError('replaceTrack is not supported in this browser', 'ERR_UNSUPPORTED_REPLACETRACK'))
  }
}

/**
 * Remove a MediaStreamTrack from the connection.
 * @param {MediaStreamTrack} track
 * @param {MediaStream} stream
 */
Peer.prototype.removeTrack = function (track, stream) {
  var self = this

  self._debug('removeSender()')

  var submap = self._senderMap.get(track)
  var sender = submap ? submap.get(stream) : null
  if (!sender) {
    self.destroy(makeError('Cannot remove track that was never added.', 'ERR_TRACK_NOT_ADDED'))
  }
  try {
    sender.removed = true
    self._pc.removeTrack(sender)
  } catch (err) {
    if (err.name === 'NS_ERROR_UNEXPECTED') {
      self._sendersAwaitingStable.push(sender) // HACK: Firefox must wait until (signalingState === stable) https://bugzilla.mozilla.org/show_bug.cgi?id=1133874
    } else {
      self.destroy(err)
    }
  }
  self._needsNegotiation()
}

/**
 * Remove a MediaStream from the connection.
 * @param {MediaStream} stream
 */
Peer.prototype.removeStream = function (stream) {
  var self = this

  self._debug('removeSenders()')

  stream.getTracks().forEach(function (track) {
    self.removeTrack(track, stream)
  })
}

Peer.prototype._needsNegotiation = function () {
  var self = this

  self._debug('_needsNegotiation')
  if (self._batchedNegotiation) return // batch synchronous renegotiations
  self._batchedNegotiation = true
  setTimeout(function () {
    self._batchedNegotiation = false
    self._debug('starting batched negotiation')
    self.negotiate()
  }, 0)
}

Peer.prototype.negotiate = function () {
  var self = this

  if (self.initiator) {
    if (self._isNegotiating) {
      self._queuedNegotiation = true
      self._debug('already negotiating, queueing')
    } else {
      self._debug('start negotiation')
      setTimeout(() => { // HACK: Chrome crashes if we immediately call createOffer
        self._createOffer()
      }, 0)
    }
  } else {
    if (!self._isNegotiating) {
      self._debug('requesting negotiation from initiator')
      self.emit('signal', { // request initiator to renegotiate
        renegotiate: true
      })
    }
  }
  self._isNegotiating = true
}

// TODO: Delete this method once readable-stream is updated to contain a default
// implementation of destroy() that automatically calls _destroy()
// See: https://github.com/nodejs/readable-stream/issues/283
Peer.prototype.destroy = function (err) {
  var self = this
  self._destroy(err, function () {})
}

Peer.prototype._destroy = function (err, cb) {
  var self = this
  if (self.destroyed) return

  self._debug('destroy (error: %s)', err && (err.message || err))

  self.readable = self.writable = false

  if (!self._readableState.ended) self.push(null)
  if (!self._writableState.finished) self.end()

  self.destroyed = true
  self.connected = false
  self._pcReady = false
  self._channelReady = false
  self._remoteTracks = null
  self._remoteStreams = null
  self._senderMap = null

  clearInterval(self._closingInterval)
  self._closingInterval = null

  clearInterval(self._interval)
  self._interval = null
  self._chunk = null
  self._cb = null

  if (self._onFinishBound) self.removeListener('finish', self._onFinishBound)
  self._onFinishBound = null

  if (self._channel) {
    try {
      self._channel.close()
    } catch (err) {}

    self._channel.onmessage = null
    self._channel.onopen = null
    self._channel.onclose = null
    self._channel.onerror = null
  }
  if (self._pc) {
    try {
      self._pc.close()
    } catch (err) {}

    self._pc.oniceconnectionstatechange = null
    self._pc.onicegatheringstatechange = null
    self._pc.onsignalingstatechange = null
    self._pc.onicecandidate = null
    self._pc.ontrack = null
    self._pc.ondatachannel = null
  }
  self._pc = null
  self._channel = null

  if (err) self.emit('error', err)
  self.emit('close')
  cb()
}

Peer.prototype._setupData = function (event) {
  var self = this
  if (!event.channel) {
    // In some situations `pc.createDataChannel()` returns `undefined` (in wrtc),
    // which is invalid behavior. Handle it gracefully.
    // See: https://github.com/feross/simple-peer/issues/163
    return self.destroy(makeError('Data channel event is missing `channel` property', 'ERR_DATA_CHANNEL'))
  }

  self._channel = event.channel
  self._channel.binaryType="arraybuffer"

  if (typeof self._channel.bufferedAmountLowThreshold === 'number') {
    self._channel.bufferedAmountLowThreshold = MAX_BUFFERED_AMOUNT
  }

  self.channelName = self._channel.label

  self._channel.onmessage = function (event) {
    self._onChannelMessage(event)
  }
  self._channel.onbufferedamountlow = function () {
    self._onChannelBufferedAmountLow()
  }
  self._channel.onopen = function () {
    self._onChannelOpen()
  }
  self._channel.onclose = function () {
    self._onChannelClose()
  }
  self._channel.onerror = function (err) {
    self.destroy(makeError(err, 'ERR_DATA_CHANNEL'))
  }

  // HACK: Chrome will sometimes get stuck in readyState "closing", let's check for this condition
  // https://bugs.chromium.org/p/chromium/issues/detail?id=882743
  var isClosing = false
  self._closingInterval = setInterval(function () { // No "onclosing" event
    if (self._channel && self._channel.readyState === 'closing') {
      if (isClosing) self._onChannelClose() // closing timed out: equivalent to onclose firing
      isClosing = true
    } else {
      isClosing = false
    }
  }, CHANNEL_CLOSING_TIMEOUT)
}

Peer.prototype._read = function () {}

Peer.prototype._write = function (chunk, encoding, cb) {
  var self = this
  if (self.destroyed) return cb(makeError('cannot write after peer is destroyed', 'ERR_DATA_CHANNEL'))

  if (self.connected) {
    try {
      self.send(chunk)
    } catch (err) {
      return self.destroy(makeError(err, 'ERR_DATA_CHANNEL'))
    }
    if (self._channel.bufferedAmount > MAX_BUFFERED_AMOUNT) {
      self._debug('start backpressure: bufferedAmount %d', self._channel.bufferedAmount)
      self._cb = cb
    } else {
      cb(null)
    }
  } else {
    self._debug('write before connect')
    self._chunk = chunk
    self._cb = cb
  }
}

// When stream finishes writing, close socket. Half open connections are not
// supported.
Peer.prototype._onFinish = function () {
  var self = this
  if (self.destroyed) return

  if (self.connected) {
    destroySoon()
  } else {
    self.once('connect', destroySoon)
  }

  // Wait a bit before destroying so the socket flushes.
  // TODO: is there a more reliable way to accomplish this?
  function destroySoon () {
    setTimeout(function () {
      self.destroy()
    }, 1000)
  }
}

Peer.prototype._startIceCompleteTimeout = function () {
  var self = this
  if (self.destroyed) return
  if (self._iceCompleteTimer) return
  self._debug('started iceComplete timeout')
  self._iceCompleteTimer = setTimeout(function () {
    if (!self._iceComplete) {
      self._iceComplete = true
      self._debug('iceComplete timeout completed')
      self.emit('iceTimeout')
      self.emit('_iceComplete')
    }
  }, self.iceCompleteTimeout)
}

Peer.prototype._createOffer = function () {
  var self = this
  if (self.destroyed) return

  self._pc.createOffer(self.offerOptions).then(function (offer) {
    if (self.destroyed) return
    if (!self.trickle && !self.allowHalfTrickle) offer.sdp = filterTrickle(offer.sdp)
    offer.sdp = self.sdpTransform(offer.sdp)
    self._pc.setLocalDescription(offer).then(onSuccess).catch(onError)

    function onSuccess () {
      self._debug('createOffer success')
      if (self.destroyed) return
      if (self.trickle || self._iceComplete) sendOffer()
      else self.once('_iceComplete', sendOffer) // wait for candidates
    }

    function onError (err) {
      self.destroy(makeError(err, 'ERR_SET_LOCAL_DESCRIPTION'))
    }

    function sendOffer () {
      if (self.destroyed) return
      var signal = self._pc.localDescription || offer
      self._debug('signal')
      self.emit('signal', {
        type: signal.type,
        sdp: signal.sdp
      })
    }
  }).catch(function (err) { self.destroy(makeError(err, 'ERR_CREATE_OFFER')) })
}

Peer.prototype._requestMissingTransceivers = function () {
  var self = this

  if (self._pc.getTransceivers) {
    self._pc.getTransceivers().forEach(transceiver => {
      if (!transceiver.mid && transceiver.sender.track) {
        self.addTransceiver(transceiver.sender.track.kind)
      }
    })
  }
}

Peer.prototype._createAnswer = function () {
  var self = this
  if (self.destroyed) return

  self._pc.createAnswer(self.answerOptions).then(function (answer) {
    if (self.destroyed) return
    if (!self.trickle && !self.allowHalfTrickle) answer.sdp = filterTrickle(answer.sdp)
    answer.sdp = self.sdpTransform(answer.sdp)
    self._pc.setLocalDescription(answer).then(onSuccess).catch(onError)

    function onSuccess () {
      if (self.destroyed) return
      if (self.trickle || self._iceComplete) sendAnswer()
      else self.once('_iceComplete', sendAnswer)
    }

    function onError (err) {
      self.destroy(makeError(err, 'ERR_SET_LOCAL_DESCRIPTION'))
    }

    function sendAnswer () {
      if (self.destroyed) return
      var signal = self._pc.localDescription || answer
      self._debug('signal')
      self.emit('signal', {
        type: signal.type,
        sdp: signal.sdp
      })
      if (!self.initiator) self._requestMissingTransceivers()
    }
  }).catch(function (err) { self.destroy(makeError(err, 'ERR_CREATE_ANSWER')) })
}

Peer.prototype._onIceStateChange = function () {
  var self = this
  if (self.destroyed) return
  var iceConnectionState = self._pc.iceConnectionState
  var iceGatheringState = self._pc.iceGatheringState

  self._debug(
    'iceStateChange (connection: %s) (gathering: %s)',
    iceConnectionState,
    iceGatheringState
  )
  self.emit('iceStateChange', iceConnectionState, iceGatheringState)

  if (iceConnectionState === 'connected' || iceConnectionState === 'completed') {
    self._pcReady = true
    self._maybeReady()
  }
  if (iceConnectionState === 'failed') {
    self.destroy(makeError('Ice connection failed.', 'ERR_ICE_CONNECTION_FAILURE'))
  }
  if (iceConnectionState === 'closed') {
    self.destroy(makeError('Ice connection closed.', 'ERR_ICE_CONNECTION_CLOSED'))
  }
}

Peer.prototype.getStats = function (cb) {
  var self = this

  // Promise-based getStats() (standard)
  if (self._pc.getStats.length === 0) {
    self._pc.getStats().then(function (res) {
      var reports = []
      res.forEach(function (report) {
        reports.push(flattenValues(report))
      })
      cb(null, reports)
    }, function (err) { cb(err) })

  // Two-parameter callback-based getStats() (deprecated, former standard)
  } else if (self._isReactNativeWebrtc) {
    self._pc.getStats(null, function (res) {
      var reports = []
      res.forEach(function (report) {
        reports.push(flattenValues(report))
      })
      cb(null, reports)
    }, function (err) { cb(err) })

  // Single-parameter callback-based getStats() (non-standard)
  } else if (self._pc.getStats.length > 0) {
    self._pc.getStats(function (res) {
      // If we destroy connection in `connect` callback this code might happen to run when actual connection is already closed
      if (self.destroyed) return

      var reports = []
      res.result().forEach(function (result) {
        var report = {}
        result.names().forEach(function (name) {
          report[name] = result.stat(name)
        })
        report.id = result.id
        report.type = result.type
        report.timestamp = result.timestamp
        reports.push(flattenValues(report))
      })
      cb(null, reports)
    }, function (err) { cb(err) })

  // Unknown browser, skip getStats() since it's anyone's guess which style of
  // getStats() they implement.
  } else {
    cb(null, [])
  }

  // statreports can come with a value array instead of properties
  function flattenValues (report) {
    if (Object.prototype.toString.call(report.values) === '[object Array]') {
      report.values.forEach(function (value) {
        Object.assign(report, value)
      })
    }
    return report
  }
}

Peer.prototype._maybeReady = function () {
  var self = this
  self._debug('maybeReady pc %s channel %s', self._pcReady, self._channelReady)
  if (self.connected || self._connecting || !self._pcReady || !self._channelReady) return

  self._connecting = true

  // HACK: We can't rely on order here, for details see https://github.com/js-platform/node-webrtc/issues/339
  function findCandidatePair () {
    if (self.destroyed) return

    self.getStats(function (err, items) {
      if (self.destroyed) return

      // Treat getStats error as non-fatal. It's not essential.
      if (err) items = []

      var remoteCandidates = {}
      var localCandidates = {}
      var candidatePairs = {}
      var foundSelectedCandidatePair = false

      items.forEach(function (item) {
        // TODO: Once all browsers support the hyphenated stats report types, remove
        // the non-hypenated ones
        if (item.type === 'remotecandidate' || item.type === 'remote-candidate') {
          remoteCandidates[item.id] = item
        }
        if (item.type === 'localcandidate' || item.type === 'local-candidate') {
          localCandidates[item.id] = item
        }
        if (item.type === 'candidatepair' || item.type === 'candidate-pair') {
          candidatePairs[item.id] = item
        }
      })

      items.forEach(function (item) {
        // Spec-compliant
        if (item.type === 'transport' && item.selectedCandidatePairId) {
          setSelectedCandidatePair(candidatePairs[item.selectedCandidatePairId])
        }

        // Old implementations
        if (
          (item.type === 'googCandidatePair' && item.googActiveConnection === 'true') ||
          ((item.type === 'candidatepair' || item.type === 'candidate-pair') && item.selected)
        ) {
          setSelectedCandidatePair(item)
        }
      })

      function setSelectedCandidatePair (selectedCandidatePair) {
        foundSelectedCandidatePair = true

        var local = localCandidates[selectedCandidatePair.localCandidateId]

        if (local && (local.ip || local.address)) {
          // Spec
          self.localAddress = local.ip || local.address
          self.localPort = Number(local.port)
        } else if (local && local.ipAddress) {
          // Firefox
          self.localAddress = local.ipAddress
          self.localPort = Number(local.portNumber)
        } else if (typeof selectedCandidatePair.googLocalAddress === 'string') {
          // TODO: remove this once Chrome 58 is released
          local = selectedCandidatePair.googLocalAddress.split(':')
          self.localAddress = local[0]
          self.localPort = Number(local[1])
        }
        if (self.localAddress) {
          self.localFamily = self.localAddress.includes(':') ? 'IPv6' : 'IPv4'
        }

        var remote = remoteCandidates[selectedCandidatePair.remoteCandidateId]

        if (remote && (remote.ip || remote.address)) {
          // Spec
          self.remoteAddress = remote.ip || remote.address
          self.remotePort = Number(remote.port)
        } else if (remote && remote.ipAddress) {
          // Firefox
          self.remoteAddress = remote.ipAddress
          self.remotePort = Number(remote.portNumber)
        } else if (typeof selectedCandidatePair.googRemoteAddress === 'string') {
          // TODO: remove this once Chrome 58 is released
          remote = selectedCandidatePair.googRemoteAddress.split(':')
          self.remoteAddress = remote[0]
          self.remotePort = Number(remote[1])
        }
        if (self.remoteAddress) {
          self.remoteFamily = self.remoteAddress.includes(':') ? 'IPv6' : 'IPv4'
        }

        self._debug(
          'connect local: %s:%s remote: %s:%s',
          self.localAddress, self.localPort, self.remoteAddress, self.remotePort
        )
      }

      // Ignore candidate pair selection in browsers like Safari 11 that do not have any local or remote candidates
      // But wait until at least 1 candidate pair is available
      if (!foundSelectedCandidatePair && (!Object.keys(candidatePairs).length || Object.keys(localCandidates).length)) {
        setTimeout(findCandidatePair, 100)
        return
      } else {
        self._connecting = false
        self.connected = true
      }

      if (self._chunk) {
        try {
          self.send(self._chunk)
        } catch (err) {
          return self.destroy(makeError(err, 'ERR_DATA_CHANNEL'))
        }
        self._chunk = null
        self._debug('sent chunk from "write before connect"')

        var cb = self._cb
        self._cb = null
        cb(null)
      }

      // If `bufferedAmountLowThreshold` and 'onbufferedamountlow' are unsupported,
      // fallback to using setInterval to implement backpressure.
      if (typeof self._channel.bufferedAmountLowThreshold !== 'number') {
        self._interval = setInterval(function () { self._onInterval() }, 150)
        if (self._interval.unref) self._interval.unref()
      }

      self._debug('connect')
      self.emit('connect')
    })
  }
  findCandidatePair()
}

Peer.prototype._onInterval = function () {
  var self = this
  if (!self._cb || !self._channel || self._channel.bufferedAmount > MAX_BUFFERED_AMOUNT) {
    return
  }
  self._onChannelBufferedAmountLow()
}

Peer.prototype._onSignalingStateChange = function () {
  var self = this
  if (self.destroyed) return

  if (self._pc.signalingState === 'stable' && !self._firstStable) {
    self._isNegotiating = false

    // HACK: Firefox doesn't yet support removing tracks when signalingState !== 'stable'
    self._debug('flushing sender queue', self._sendersAwaitingStable)
    self._sendersAwaitingStable.forEach(function (sender) {
      self._pc.removeTrack(sender)
      self._queuedNegotiation = true
    })
    self._sendersAwaitingStable = []

    if (self._queuedNegotiation) {
      self._debug('flushing negotiation queue')
      self._queuedNegotiation = false
      self._needsNegotiation() // negotiate again
    }

    self._debug('negotiate')
    self.emit('negotiate')
  }
  self._firstStable = false

  self._debug('signalingStateChange %s', self._pc.signalingState)
  self.emit('signalingStateChange', self._pc.signalingState)
}

Peer.prototype._onIceCandidate = function (event) {
  var self = this
  if (self.destroyed) return
  if (event.candidate && self.trickle) {
    self.emit('signal', {
      candidate: {
        candidate: event.candidate.candidate,
        sdpMLineIndex: event.candidate.sdpMLineIndex,
        sdpMid: event.candidate.sdpMid
      }
    })
  } else if (!event.candidate && !self._iceComplete) {
    self._iceComplete = true
    self.emit('_iceComplete')
  }
  // as soon as we've received one valid candidate start timeout
  if (event.candidate) {
    self._startIceCompleteTimeout()
  }
}

Peer.prototype._onChannelMessage = function (event) {
  var self = this
  if (self.destroyed) return
  var data = event.data
  if (data instanceof ArrayBuffer) data = Buffer.from(data)
  self.push(data)
}

Peer.prototype._onChannelBufferedAmountLow = function () {
  var self = this
  if (self.destroyed || !self._cb) return
  self._debug('ending backpressure: bufferedAmount %d', self._channel.bufferedAmount)
  var cb = self._cb
  self._cb = null
  cb(null)
}

Peer.prototype._onChannelOpen = function () {
  var self = this
  if (self.connected || self.destroyed) return
  self._debug('on channel open')
  self._channelReady = true
  self._maybeReady()
}

Peer.prototype._onChannelClose = function () {
  var self = this
  if (self.destroyed) return
  self._debug('on channel close')
  self.destroy()
}

Peer.prototype._onTrack = function (event) {
  var self = this
  if (self.destroyed) return

  event.streams.forEach(function (eventStream) {
    self._debug('on track')
    self.emit('track', event.track, eventStream)

    self._remoteTracks.push({
      track: event.track,
      stream: eventStream
    })

    if (self._remoteStreams.some(function (remoteStream) {
      return remoteStream.id === eventStream.id
    })) return // Only fire one 'stream' event, even though there may be multiple tracks per stream

    self._remoteStreams.push(eventStream)
    setTimeout(function () {
      self.emit('stream', eventStream) // ensure all tracks have been added
    }, 0)
  })
}

Peer.prototype._debug = function () {
  var self = this
  var args = [].slice.call(arguments)
  args[0] = '[' + self._id + '] ' + args[0]
  debug.apply(null, args)
}

// HACK: Filter trickle lines when trickle is disabled #354
function filterTrickle (sdp) {
  return sdp.replace(/a=ice-options:tricklesn/g, '')
}

function makeError (message, code) {
  var err = new Error(message)
  err.code = code
  return err
}

}).call(this,require("buffer").Buffer)
},{"buffer":3,"debug":25,"get-browser-rtc":6,"inherits":8,"randombytes":13,"readable-stream":22}],25:[function(require,module,exports){
(function (process){
/* eslint-env browser */

/**
 * This is the web browser implementation of `debug()`.
 */

exports.log = log;
exports.formatArgs = formatArgs;
exports.save = save;
exports.load = load;
exports.useColors = useColors;
exports.storage = localstorage();

/**
 * Colors.
 */

exports.colors = [
	'#0000CC',
	'#0000FF',
	'#0033CC',
	'#0033FF',
	'#0066CC',
	'#0066FF',
	'#0099CC',
	'#0099FF',
	'#00CC00',
	'#00CC33',
	'#00CC66',
	'#00CC99',
	'#00CCCC',
	'#00CCFF',
	'#3300CC',
	'#3300FF',
	'#3333CC',
	'#3333FF',
	'#3366CC',
	'#3366FF',
	'#3399CC',
	'#3399FF',
	'#33CC00',
	'#33CC33',
	'#33CC66',
	'#33CC99',
	'#33CCCC',
	'#33CCFF',
	'#6600CC',
	'#6600FF',
	'#6633CC',
	'#6633FF',
	'#66CC00',
	'#66CC33',
	'#9900CC',
	'#9900FF',
	'#9933CC',
	'#9933FF',
	'#99CC00',
	'#99CC33',
	'#CC0000',
	'#CC0033',
	'#CC0066',
	'#CC0099',
	'#CC00CC',
	'#CC00FF',
	'#CC3300',
	'#CC3333',
	'#CC3366',
	'#CC3399',
	'#CC33CC',
	'#CC33FF',
	'#CC6600',
	'#CC6633',
	'#CC9900',
	'#CC9933',
	'#CCCC00',
	'#CCCC33',
	'#FF0000',
	'#FF0033',
	'#FF0066',
	'#FF0099',
	'#FF00CC',
	'#FF00FF',
	'#FF3300',
	'#FF3333',
	'#FF3366',
	'#FF3399',
	'#FF33CC',
	'#FF33FF',
	'#FF6600',
	'#FF6633',
	'#FF9900',
	'#FF9933',
	'#FFCC00',
	'#FFCC33'
];

/**
 * Currently only WebKit-based Web Inspectors, Firefox >= v31,
 * and the Firebug extension (any Firefox version) are known
 * to support "%c" CSS customizations.
 *
 * TODO: add a `localStorage` variable to explicitly enable/disable colors
 */

// eslint-disable-next-line complexity
function useColors() {
	// NB: In an Electron preload script, document will be defined but not fully
	// initialized. Since we know we're in Chrome, we'll just detect this case
	// explicitly
	if (typeof window !== 'undefined' && window.process && (window.process.type === 'renderer' || window.process.__nwjs)) {
		return true;
	}

	// Internet Explorer and Edge do not support colors.
	if (typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/(edge|trident)/(d+)/)) {
		return false;
	}

	// Is webkit? http://stackoverflow.com/a/16459606/376773
	// document is undefined in react-native: https://github.com/facebook/react-native/pull/1632
	return (typeof document !== 'undefined' && document.documentElement && document.documentElement.style && document.documentElement.style.WebkitAppearance) ||
		// Is firebug? http://stackoverflow.com/a/398120/376773
		(typeof window !== 'undefined' && window.console && (window.console.firebug || (window.console.exception && window.console.table))) ||
		// Is firefox >= v31?
		// https://developer.mozilla.org/en-US/docs/Tools/Web_Console#Styling_messages
		(typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/firefox/(d+)/) && parseInt(RegExp.$1, 10) >= 31) ||
		// Double check webkit in userAgent just in case we are in a worker
		(typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/applewebkit/(d+)/));
}

/**
 * Colorize log arguments if enabled.
 *
 * @api public
 */

function formatArgs(args) {
	args[0] = (this.useColors ? '%c' : '') +
		this.namespace +
		(this.useColors ? ' %c' : ' ') +
		args[0] +
		(this.useColors ? '%c ' : ' ') +
		'+' + module.exports.humanize(this.diff);

	if (!this.useColors) {
		return;
	}

	const c="color: " + this.color;
	args.splice(1, 0, c, 'color: inherit');

	// The final "%c" is somewhat tricky, because there could be other
	// arguments passed either before or after the %c, so we need to
	// figure out the correct index to insert the CSS into
	let index = 0;
	let lastC = 0;
	args[0].replace(/%[a-zA-Z%]/g, match => {
		if (match === '%%') {
			return;
		}
		index++;
		if (match === '%c') {
			// We only are interested in the *last* %c
			// (the user may have provided their own)
			lastC = index;
		}
	});

	args.splice(lastC, 0, c);
}

/**
 * Invokes `console.log()` when available.
 * No-op when `console.log` is not a "function".
 *
 * @api public
 */
function log(...args) {
	// This hackery is required for IE8/9, where
	// the `console.log` function doesn't have 'apply'
	return typeof console === 'object' &&
		console.log &&
		console.log(...args);
}

/**
 * Save `namespaces`.
 *
 * @param {String} namespaces
 * @api private
 */
function save(namespaces) {
	try {
		if (namespaces) {
			exports.storage.setItem('debug', namespaces);
		} else {
			exports.storage.removeItem('debug');
		}
	} catch (error) {
		// Swallow
		// XXX (@Qix-) should we be logging these?
	}
}

/**
 * Load `namespaces`.
 *
 * @return {String} returns the previously persisted debug modes
 * @api private
 */
function load() {
	let r;
	try {
		r = exports.storage.getItem('debug');
	} catch (error) {
		// Swallow
		// XXX (@Qix-) should we be logging these?
	}

	// If debug isn't set in LS, and we're in Electron, try to load $DEBUG
	if (!r && typeof process !== 'undefined' && 'env' in process) {
		r = process.env.DEBUG;
	}

	return r;
}

/**
 * Localstorage attempts to return the localstorage.
 *
 * This is necessary because safari throws
 * when a user disables cookies/localstorage
 * and you attempt to access it.
 *
 * @return {LocalStorage}
 * @api private
 */

function localstorage() {
	try {
		// TVMLKit (Apple TV JS Runtime) does not have a window object, just localStorage in the global context
		// The Browser also has localStorage in the global context.
		return localStorage;
	} catch (error) {
		// Swallow
		// XXX (@Qix-) should we be logging these?
	}
}

module.exports = require('./common')(exports);

const {formatters} = module.exports;

/**
 * Map %j to `JSON.stringify()`, since no Web Inspectors do that by default.
 */

formatters.j = function (v) {
	try {
		return JSON.stringify(v);
	} catch (error) {
		return '[UnexpectedJSONParseError]: ' + error.message;
	}
};

}).call(this,require('_process'))
},{"./common":26,"_process":12}],26:[function(require,module,exports){

/**
 * This is the common logic for both the Node.js and web browser
 * implementations of `debug()`.
 */

function setup(env) {
	createDebug.debug = createDebug;
	createDebug.default = createDebug;
	createDebug.coerce = coerce;
	createDebug.disable = disable;
	createDebug.enable = enable;
	createDebug.enabled = enabled;
	createDebug.humanize = require('ms');

	Object.keys(env).forEach(key => {
		createDebug[key] = env[key];
	});

	/**
	* Active `debug` instances.
	*/
	createDebug.instances = [];

	/**
	* The currently active debug mode names, and names to skip.
	*/

	createDebug.names = [];
	createDebug.skips = [];

	/**
	* Map of special "%n" handling functions, for the debug "format" argument.
	*
	* Valid key names are a single, lower or upper-case letter, i.e. "n" and "N".
	*/
	createDebug.formatters = {};

	/**
	* Selects a color for a debug namespace
	* @param {String} namespace The namespace string for the for the debug instance to be colored
	* @return {Number|String} An ANSI color code for the given namespace
	* @api private
	*/
	function selectColor(namespace) {
		let hash = 0;

		for (let i = 0; i < namespace.length; i++) {
			hash = ((hash << 5) - hash) + namespace.charCodeAt(i);
			hash |= 0; // Convert to 32bit integer
		}

		return createDebug.colors[Math.abs(hash) % createDebug.colors.length];
	}
	createDebug.selectColor = selectColor;

	/**
	* Create a debugger with the given `namespace`.
	*
	* @param {String} namespace
	* @return {Function}
	* @api public
	*/
	function createDebug(namespace) {
		let prevTime;

		function debug(...args) {
			// Disabled?
			if (!debug.enabled) {
				return;
			}

			const self = debug;

			// Set `diff` timestamp
			const curr = Number(new Date());
			const ms = curr - (prevTime || curr);
			self.diff = ms;
			self.prev = prevTime;
			self.curr = curr;
			prevTime = curr;

			args[0] = createDebug.coerce(args[0]);

			if (typeof args[0] !== 'string') {
				// Anything else let's inspect with %O
				args.unshift('%O');
			}

			// Apply any `formatters` transformations
			let index = 0;
			args[0] = args[0].replace(/%([a-zA-Z%])/g, (match, format) => {
				// If we encounter an escaped % then don't increase the array index
				if (match === '%%') {
					return match;
				}
				index++;
				const formatter = createDebug.formatters[format];
				if (typeof formatter === 'function') {
					const val = args[index];
					match = formatter.call(self, val);

					// Now we need to remove `args[index]` since it's inlined in the `format`
					args.splice(index, 1);
					index--;
				}
				return match;
			});

			// Apply env-specific formatting (colors, etc.)
			createDebug.formatArgs.call(self, args);

			const logFn = self.log || createDebug.log;
			logFn.apply(self, args);
		}

		debug.namespace = namespace;
		debug.enabled = createDebug.enabled(namespace);
		debug.useColors = createDebug.useColors();
		debug.color = selectColor(namespace);
		debug.destroy = destroy;
		debug.extend = extend;
		// Debug.formatArgs = formatArgs;
		// debug.rawLog = rawLog;

		// env-specific initialization logic for debug instances
		if (typeof createDebug.init === 'function') {
			createDebug.init(debug);
		}

		createDebug.instances.push(debug);

		return debug;
	}

	function destroy() {
		const index = createDebug.instances.indexOf(this);
		if (index !== -1) {
			createDebug.instances.splice(index, 1);
			return true;
		}
		return false;
	}

	function extend(namespace, delimiter) {
		const newDebug = createDebug(this.namespace + (typeof delimiter === 'undefined' ? ':' : delimiter) + namespace);
		newDebug.log = this.log;
		return newDebug;
	}

	/**
	* Enables a debug mode by namespaces. This can include modes
	* separated by a colon and wildcards.
	*
	* @param {String} namespaces
	* @api public
	*/
	function enable(namespaces) {
		createDebug.save(namespaces);

		createDebug.names = [];
		createDebug.skips = [];

		let i;
		const split = (typeof namespaces === 'string' ? namespaces : '').split(/[s,]+/);
		const len = split.length;

		for (i = 0; i < len; i++) {
			if (!split[i]) {
				// ignore empty strings
				continue;
			}

			namespaces = split[i].replace(/*/g, '.*?');

			if (namespaces[0] === '-') {
				createDebug.skips.push(new RegExp('^' + namespaces.substr(1) + '
));
			} else {
				createDebug.names.push(new RegExp('^' + namespaces + '
));
			}
		}

		for (i = 0; i < createDebug.instances.length; i++) {
			const instance = createDebug.instances[i];
			instance.enabled = createDebug.enabled(instance.namespace);
		}
	}

	/**
	* Disable debug output.
	*
	* @return {String} namespaces
	* @api public
	*/
	function disable() {
		const namespaces = [
			...createDebug.names.map(toNamespace),
			...createDebug.skips.map(toNamespace).map(namespace => '-' + namespace)
		].join(',');
		createDebug.enable('');
		return namespaces;
	}

	/**
	* Returns true if the given mode name is enabled, false otherwise.
	*
	* @param {String} name
	* @return {Boolean}
	* @api public
	*/
	function enabled(name) {
		if (name[name.length - 1] === '*') {
			return true;
		}

		let i;
		let len;

		for (i = 0, len = createDebug.skips.length; i < len; i++) {
			if (createDebug.skips[i].test(name)) {
				return false;
			}
		}

		for (i = 0, len = createDebug.names.length; i < len; i++) {
			if (createDebug.names[i].test(name)) {
				return true;
			}
		}

		return false;
	}

	/**
	* Convert regexp to namespace
	*
	* @param {RegExp} regxep
	* @return {String} namespace
	* @api private
	*/
	function toNamespace(regexp) {
		return regexp.toString()
			.substring(2, regexp.toString().length - 2)
			.replace(/.*?$/, '*');
	}

	/**
	* Coerce `val`.
	*
	* @param {Mixed} val
	* @return {Mixed}
	* @api private
	*/
	function coerce(val) {
		if (val instanceof Error) {
			return val.stack || val.message;
		}
		return val;
	}

	createDebug.enable(createDebug.load());

	return createDebug;
}

module.exports = setup;

},{"ms":27}],27:[function(require,module,exports){
/**
 * Helpers.
 */

var s = 1000;
var m = s * 60;
var h = m * 60;
var d = h * 24;
var w = d * 7;
var y = d * 365.25;

/**
 * Parse or format the given `val`.
 *
 * Options:
 *
 *  - `long` verbose formatting [false]
 *
 * @param {String|Number} val
 * @param {Object} [options]
 * @throws {Error} throw an error if val is not a non-empty string or a number
 * @return {String|Number}
 * @api public
 */

module.exports = function(val, options) {
  options = options || {};
  var type = typeof val;
  if (type === 'string' && val.length > 0) {
    return parse(val);
  } else if (type === 'number' && isNaN(val) === false) {
    return options.long ? fmtLong(val) : fmtShort(val);
  }
  throw new Error(
    'val is not a non-empty string or a valid number. val=" +
      JSON.stringify(val)
  );
};

/**
 * Parse the given `str` and return milliseconds.
 *
 * @param {String} str
 * @return {Number}
 * @api private
 */

function parse(str) {
  str = String(str);
  if (str.length > 100) {
    return;
  }
  var match = /^((?:d+)?-?d?.?d+) *(milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|years?|yrs?|y)?$/i.exec(
    str
  );
  if (!match) {
    return;
  }
  var n = parseFloat(match[1]);
  var type = (match[2] || "ms').toLowerCase();
  switch (type) {
    case 'years':
    case 'year':
    case 'yrs':
    case 'yr':
    case 'y':
      return n * y;
    case 'weeks':
    case 'week':
    case 'w':
      return n * w;
    case 'days':
    case 'day':
    case 'd':
      return n * d;
    case 'hours':
    case 'hour':
    case 'hrs':
    case 'hr':
    case 'h':
      return n * h;
    case 'minutes':
    case 'minute':
    case 'mins':
    case 'min':
    case 'm':
      return n * m;
    case 'seconds':
    case 'second':
    case 'secs':
    case 'sec':
    case 's':
      return n * s;
    case 'milliseconds':
    case 'millisecond':
    case 'msecs':
    case 'msec':
    case 'ms':
      return n;
    default:
      return undefined;
  }
}

/**
 * Short format for `ms`.
 *
 * @param {Number} ms
 * @return {String}
 * @api private
 */

function fmtShort(ms) {
  var msAbs = Math.abs(ms);
  if (msAbs >= d) {
    return Math.round(ms / d) + 'd';
  }
  if (msAbs >= h) {
    return Math.round(ms / h) + 'h';
  }
  if (msAbs >= m) {
    return Math.round(ms / m) + 'm';
  }
  if (msAbs >= s) {
    return Math.round(ms / s) + 's';
  }
  return ms + 'ms';
}

/**
 * Long format for `ms`.
 *
 * @param {Number} ms
 * @return {String}
 * @api private
 */

function fmtLong(ms) {
  var msAbs = Math.abs(ms);
  if (msAbs >= d) {
    return plural(ms, msAbs, d, 'day');
  }
  if (msAbs >= h) {
    return plural(ms, msAbs, h, 'hour');
  }
  if (msAbs >= m) {
    return plural(ms, msAbs, m, 'minute');
  }
  if (msAbs >= s) {
    return plural(ms, msAbs, s, 'second');
  }
  return ms + ' ms';
}

/**
 * Pluralization helper.
 */

function plural(ms, msAbs, n, name) {
  var isPlural = msAbs >= n * 1.5;
  return Math.round(ms / n) + ' ' + name + (isPlural ? 's' : '');
}

},{}],28:[function(require,module,exports){
// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.

'use strict';

/*<replacement>*/

var Buffer = require('safe-buffer').Buffer;
/*</replacement>*/

var isEncoding = Buffer.isEncoding || function (encoding) {
  encoding = '' + encoding;
  switch (encoding && encoding.toLowerCase()) {
    case 'hex':case 'utf8':case 'utf-8':case 'ascii':case 'binary':case 'base64':case 'ucs2':case 'ucs-2':case 'utf16le':case 'utf-16le':case 'raw':
      return true;
    default:
      return false;
  }
};

function _normalizeEncoding(enc) {
  if (!enc) return 'utf8';
  var retried;
  while (true) {
    switch (enc) {
      case 'utf8':
      case 'utf-8':
        return 'utf8';
      case 'ucs2':
      case 'ucs-2':
      case 'utf16le':
      case 'utf-16le':
        return 'utf16le';
      case 'latin1':
      case 'binary':
        return 'latin1';
      case 'base64':
      case 'ascii':
      case 'hex':
        return enc;
      default:
        if (retried) return; // undefined
        enc = ('' + enc).toLowerCase();
        retried = true;
    }
  }
};

// Do not cache `Buffer.isEncoding` when checking encoding names as some
// modules monkey-patch it to support additional encodings
function normalizeEncoding(enc) {
  var nenc = _normalizeEncoding(enc);
  if (typeof nenc !== 'string' && (Buffer.isEncoding === isEncoding || !isEncoding(enc))) throw new Error('Unknown encoding: ' + enc);
  return nenc || enc;
}

// StringDecoder provides an interface for efficiently splitting a series of
// buffers into a series of JS strings without breaking apart multi-byte
// characters.
exports.StringDecoder = StringDecoder;
function StringDecoder(encoding) {
  this.encoding = normalizeEncoding(encoding);
  var nb;
  switch (this.encoding) {
    case 'utf16le':
      this.text = utf16Text;
      this.end = utf16End;
      nb = 4;
      break;
    case 'utf8':
      this.fillLast = utf8FillLast;
      nb = 4;
      break;
    case 'base64':
      this.text = base64Text;
      this.end = base64End;
      nb = 3;
      break;
    default:
      this.write = simpleWrite;
      this.end = simpleEnd;
      return;
  }
  this.lastNeed = 0;
  this.lastTotal = 0;
  this.lastChar = Buffer.allocUnsafe(nb);
}

StringDecoder.prototype.write = function (buf) {
  if (buf.length === 0) return '';
  var r;
  var i;
  if (this.lastNeed) {
    r = this.fillLast(buf);
    if (r === undefined) return '';
    i = this.lastNeed;
    this.lastNeed = 0;
  } else {
    i = 0;
  }
  if (i < buf.length) return r ? r + this.text(buf, i) : this.text(buf, i);
  return r || '';
};

StringDecoder.prototype.end = utf8End;

// Returns only complete characters in a Buffer
StringDecoder.prototype.text = utf8Text;

// Attempts to complete a partial non-UTF-8 character using bytes from a Buffer
StringDecoder.prototype.fillLast = function (buf) {
  if (this.lastNeed <= buf.length) {
    buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, this.lastNeed);
    return this.lastChar.toString(this.encoding, 0, this.lastTotal);
  }
  buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, buf.length);
  this.lastNeed -= buf.length;
};

// Checks the type of a UTF-8 byte, whether it's ASCII, a leading byte, or a
// continuation byte. If an invalid byte is detected, -2 is returned.
function utf8CheckByte(byte) {
  if (byte <= 0x7F) return 0;else if (byte >> 5 === 0x06) return 2;else if (byte >> 4 === 0x0E) return 3;else if (byte >> 3 === 0x1E) return 4;
  return byte >> 6 === 0x02 ? -1 : -2;
}

// Checks at most 3 bytes at the end of a Buffer in order to detect an
// incomplete multi-byte UTF-8 character. The total number of bytes (2, 3, or 4)
// needed to complete the UTF-8 character (if applicable) are returned.
function utf8CheckIncomplete(self, buf, i) {
  var j = buf.length - 1;
  if (j < i) return 0;
  var nb = utf8CheckByte(buf[j]);
  if (nb >= 0) {
    if (nb > 0) self.lastNeed = nb - 1;
    return nb;
  }
  if (--j < i || nb === -2) return 0;
  nb = utf8CheckByte(buf[j]);
  if (nb >= 0) {
    if (nb > 0) self.lastNeed = nb - 2;
    return nb;
  }
  if (--j < i || nb === -2) return 0;
  nb = utf8CheckByte(buf[j]);
  if (nb >= 0) {
    if (nb > 0) {
      if (nb === 2) nb = 0;else self.lastNeed = nb - 3;
    }
    return nb;
  }
  return 0;
}

// Validates as many continuation bytes for a multi-byte UTF-8 character as
// needed or are available. If we see a non-continuation byte where we expect
// one, we "replace" the validated continuation bytes we've seen so far with
// a single UTF-8 replacement character ('ufffd'), to match v8's UTF-8 decoding
// behavior. The continuation byte check is included three times in the case
// where all of the continuation bytes for a character exist in the same buffer.
// It is also done this way as a slight performance increase instead of using a
// loop.
function utf8CheckExtraBytes(self, buf, p) {
  if ((buf[0] & 0xC0) !== 0x80) {
    self.lastNeed = 0;
    return 'ufffd';
  }
  if (self.lastNeed > 1 && buf.length > 1) {
    if ((buf[1] & 0xC0) !== 0x80) {
      self.lastNeed = 1;
      return 'ufffd';
    }
    if (self.lastNeed > 2 && buf.length > 2) {
      if ((buf[2] & 0xC0) !== 0x80) {
        self.lastNeed = 2;
        return 'ufffd';
      }
    }
  }
}

// Attempts to complete a multi-byte UTF-8 character using bytes from a Buffer.
function utf8FillLast(buf) {
  var p = this.lastTotal - this.lastNeed;
  var r = utf8CheckExtraBytes(this, buf, p);
  if (r !== undefined) return r;
  if (this.lastNeed <= buf.length) {
    buf.copy(this.lastChar, p, 0, this.lastNeed);
    return this.lastChar.toString(this.encoding, 0, this.lastTotal);
  }
  buf.copy(this.lastChar, p, 0, buf.length);
  this.lastNeed -= buf.length;
}

// Returns all complete UTF-8 characters in a Buffer. If the Buffer ended on a
// partial character, the character's bytes are buffered until the required
// number of bytes are available.
function utf8Text(buf, i) {
  var total = utf8CheckIncomplete(this, buf, i);
  if (!this.lastNeed) return buf.toString('utf8', i);
  this.lastTotal = total;
  var end = buf.length - (total - this.lastNeed);
  buf.copy(this.lastChar, 0, end);
  return buf.toString('utf8', i, end);
}

// For UTF-8, a replacement character is added when ending on a partial
// character.
function utf8End(buf) {
  var r = buf && buf.length ? this.write(buf) : '';
  if (this.lastNeed) return r + 'ufffd';
  return r;
}

// UTF-16LE typically needs two bytes per character, but even if we have an even
// number of bytes available, we need to check if we end on a leading/high
// surrogate. In that case, we need to wait for the next two bytes in order to
// decode the last character properly.
function utf16Text(buf, i) {
  if ((buf.length - i) % 2 === 0) {
    var r = buf.toString('utf16le', i);
    if (r) {
      var c = r.charCodeAt(r.length - 1);
      if (c >= 0xD800 && c <= 0xDBFF) {
        this.lastNeed = 2;
        this.lastTotal = 4;
        this.lastChar[0] = buf[buf.length - 2];
        this.lastChar[1] = buf[buf.length - 1];
        return r.slice(0, -1);
      }
    }
    return r;
  }
  this.lastNeed = 1;
  this.lastTotal = 2;
  this.lastChar[0] = buf[buf.length - 1];
  return buf.toString('utf16le', i, buf.length - 1);
}

// For UTF-16LE we do not explicitly append special replacement characters if we
// end on a partial character, we simply let v8 handle that.
function utf16End(buf) {
  var r = buf && buf.length ? this.write(buf) : '';
  if (this.lastNeed) {
    var end = this.lastTotal - this.lastNeed;
    return r + this.lastChar.toString('utf16le', 0, end);
  }
  return r;
}

function base64Text(buf, i) {
  var n = (buf.length - i) % 3;
  if (n === 0) return buf.toString('base64', i);
  this.lastNeed = 3 - n;
  this.lastTotal = 3;
  if (n === 1) {
    this.lastChar[0] = buf[buf.length - 1];
  } else {
    this.lastChar[0] = buf[buf.length - 2];
    this.lastChar[1] = buf[buf.length - 1];
  }
  return buf.toString('base64', i, buf.length - n);
}

function base64End(buf) {
  var r = buf && buf.length ? this.write(buf) : '';
  if (this.lastNeed) return r + this.lastChar.toString('base64', 0, 3 - this.lastNeed);
  return r;
}

// Pass bytes on through for single-byte encodings (e.g. ascii, latin1, hex)
function simpleWrite(buf) {
  return buf.toString(this.encoding);
}

function simpleEnd(buf) {
  return buf && buf.length ? this.write(buf) : '';
}
},{"safe-buffer":23}],29:[function(require,module,exports){
(function (setImmediate,clearImmediate){
var nextTick = require('process/browser.js').nextTick;
var apply = Function.prototype.apply;
var slice = Array.prototype.slice;
var immediateIds = {};
var nextImmediateId = 0;

// DOM APIs, for completeness

exports.setTimeout = function() {
  return new Timeout(apply.call(setTimeout, window, arguments), clearTimeout);
};
exports.setInterval = function() {
  return new Timeout(apply.call(setInterval, window, arguments), clearInterval);
};
exports.clearTimeout =
exports.clearInterval = function(timeout) { timeout.close(); };

function Timeout(id, clearFn) {
  this._id = id;
  this._clearFn = clearFn;
}
Timeout.prototype.unref = Timeout.prototype.ref = function() {};
Timeout.prototype.close = function() {
  this._clearFn.call(window, this._id);
};

// Does not start the time, just sets up the members needed.
exports.enroll = function(item, msecs) {
  clearTimeout(item._idleTimeoutId);
  item._idleTimeout = msecs;
};

exports.unenroll = function(item) {
  clearTimeout(item._idleTimeoutId);
  item._idleTimeout = -1;
};

exports._unrefActive = exports.active = function(item) {
  clearTimeout(item._idleTimeoutId);

  var msecs = item._idleTimeout;
  if (msecs >= 0) {
    item._idleTimeoutId = setTimeout(function onTimeout() {
      if (item._onTimeout)
        item._onTimeout();
    }, msecs);
  }
};

// That's not how node.js implements it but the exposed api is the same.
exports.setImmediate = typeof setImmediate === "function" ? setImmediate : function(fn) {
  var id = nextImmediateId++;
  var args = arguments.length < 2 ? false : slice.call(arguments, 1);

  immediateIds[id] = true;

  nextTick(function onNextTick() {
    if (immediateIds[id]) {
      // fn.call() is faster so we optimize for the common use-case
      // @see http://jsperf.com/call-apply-segu
      if (args) {
        fn.apply(null, args);
      } else {
        fn.call(null);
      }
      // Prevent ids from leaking
      exports.clearImmediate(id);
    }
  });

  return id;
};

exports.clearImmediate = typeof clearImmediate === "function" ? clearImmediate : function(id) {
  delete immediateIds[id];
};
}).call(this,require("timers").setImmediate,require("timers").clearImmediate)
},{"process/browser.js":12,"timers":29}],30:[function(require,module,exports){
(function (global){

/**
 * Module exports.
 */

module.exports = deprecate;

/**
 * Mark that a method should not be used.
 * Returns a modified function which warns once by default.
 *
 * If `localStorage.noDeprecation = true` is set, then it is a no-op.
 *
 * If `localStorage.throwDeprecation = true` is set, then deprecated functions
 * will throw an Error when invoked.
 *
 * If `localStorage.traceDeprecation = true` is set, then deprecated functions
 * will invoke `console.trace()` instead of `console.error()`.
 *
 * @param {Function} fn - the function to deprecate
 * @param {String} msg - the string to print to the console when `fn` is invoked
 * @returns {Function} a new "deprecated" version of `fn`
 * @api public
 */

function deprecate (fn, msg) {
  if (config('noDeprecation')) {
    return fn;
  }

  var warned = false;
  function deprecated() {
    if (!warned) {
      if (config('throwDeprecation')) {
        throw new Error(msg);
      } else if (config('traceDeprecation')) {
        console.trace(msg);
      } else {
        console.warn(msg);
      }
      warned = true;
    }
    return fn.apply(this, arguments);
  }

  return deprecated;
}

/**
 * Checks `localStorage` for boolean values for the given `name`.
 *
 * @param {String} name
 * @returns {Boolean}
 * @api private
 */

function config (name) {
  // accessing global.localStorage can trigger a DOMException in sandboxed iframes
  try {
    if (!global.localStorage) return false;
  } catch (_) {
    return false;
  }
  var val = global.localStorage[name];
  if (null == val) return false;
  return String(val).toLowerCase() === 'true';
}

}).call(this,typeof global !== "undefined" ? global : typeof self !== "undefined" ? self : typeof window !== "undefined" ? window : {})
},{}],31:[function(require,module,exports){

let Peer = require('simple-peer')
let socket = io()
const video = document.querySelector('video')
const filter = document.querySelector('#filter')
const checkboxTheme = document.querySelector('#theme')
let client = {}
let currentFilter
//get stream
navigator.mediaDevices.getUserMedia({ video: true, audio: true })
    .then(stream => {
        socket.emit('NewClient')
        video.srcObject = stream
        video.play()

        filter.addEventListener('change', (event) => {
            currentFilter = event.target.value
            video.style.filter = currentFilter
            SendFilter(currentFilter)
            event.preventDefault
        })

        //used to initialize a peer
        function InitPeer(type) {
            let peer = new Peer({ initiator: (type == 'init') ? true : false, stream: stream, trickle: false })
            peer.on('stream', function (stream) {
                CreateVideo(stream)
            })
            //This isn't working in chrome; works perfectly in firefox.
            // peer.on('close', function () {
            //     document.getElementById("peerVideo").remove();
            //     peer.destroy()
            // })
            peer.on('data', function (data) {
                let decodedData = new TextDecoder('utf-8').decode(data)
                let peervideo = document.querySelector('#peerVideo')
                peervideo.style.filter = decodedData
            })
            return peer
        }

        //for peer of type init
        function MakePeer() {
            client.gotAnswer = false
            let peer = InitPeer('init')
            peer.on('signal', function (data) {
                if (!client.gotAnswer) {
                    socket.emit('Offer', data)
                }
            })
            client.peer = peer
        }

        //for peer of type not init
        function FrontAnswer(offer) {
            let peer = InitPeer('notInit')
            peer.on('signal', (data) => {
                socket.emit('Answer', data)
            })
            peer.signal(offer)
            client.peer = peer
        }

        function SignalAnswer(answer) {
            client.gotAnswer = true
            let peer = client.peer
            peer.signal(answer)
        }

        function CreateVideo(stream) {
            CreateDiv()

            let video = document.createElement('video')
            video.id = 'peerVideo'
            video.srcObject = stream
            video.setAttribute('class', 'embed-responsive-item')
            document.querySelector('#peerDiv').appendChild(video)
            video.play()
            //wait for 1 sec
            setTimeout(() => SendFilter(currentFilter), 1000)

            video.addEventListener('click', () => {
                if (video.volume != 0)
                    video.volume = 0
                else
                    video.volume = 1
            })

        }

        function SessionActive() {
            document.write('Session Active. Please come back later')
        }

        function SendFilter(filter) {
            if (client.peer) {
                client.peer.send(filter)
            }
        }

        function RemovePeer() {
            document.getElementById("peerVideo").remove();
            document.getElementById("muteText").remove();
            if (client.peer) {
                client.peer.destroy()
            }
        }

        socket.on('BackOffer', FrontAnswer)
        socket.on('BackAnswer', SignalAnswer)
        socket.on('SessionActive', SessionActive)
        socket.on('CreatePeer', MakePeer)
        socket.on('Disconnect', RemovePeer)

    })
    .catch(err => document.write(err))

checkboxTheme.addEventListener('click', () => {
    if (checkboxTheme.checked == true) {
        document.body.style.backgroundColor="#212529"
        if (document.querySelector('#muteText')) {
            document.querySelector('#muteText').style.color = "#fff"
        }

    }
    else {
        document.body.style.backgroundColor="#fff"
        if (document.querySelector('#muteText')) {
            document.querySelector('#muteText').style.color = "#212529"
        }
    }
}
)

function CreateDiv() {
    let div = document.createElement('div')
    div.setAttribute('class', "centered")
    div.id = "muteText"
    div.innerHTML = "Click to Mute/Unmute"
    document.querySelector('#peerDiv').appendChild(div)
    if (checkboxTheme.checked == true)
        document.querySelector('#muteText').style.color = "#fff"
}

},{"simple-peer":24}]},{},[31]);

Read Also: Node.js Express Zoom Clone Video & Text Group Chat Using Peerjs Socket.io & WebRTC Library in Javascript

Final Words

What we learned through this article is to Build Node.js P2P Zoom Clone Video Chat Using simple-peer & WebRTC Library in Javascript. Also if you have any doubts please leave a comment via the comment box. And we ask that you benefit everyone who shared this article with your friends.    

Hi, I'm Ranjith a full-time Blogger, YouTuber, Affiliate Marketer, & founder of Coding Deekshi. Here, I post about programming to help developers.

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