How to use the readable-stream/duplex.call function in readable-stream

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}

this.on('pipe', function (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function (src) {
      src.removeListener('error', piper)
    })
  }
  else if (Buffer.isBuffer(callback))
    this.append(callback)
  else if (Array.isArray(callback)) {
    callback.forEach(function (b) {
      Buffer.isBuffer(b) && this.append(b)
    }.bind(this))
  }

  DuplexStream.call(this)
}

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}

this.on('pipe', function (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function (src) {
      src.removeListener('error', piper)
    })
  }
  else if (Buffer.isBuffer(callback))
    this.append(callback)
  else if (Array.isArray(callback)) {
    callback.forEach(function (b) {
      Buffer.isBuffer(b) && this.append(b)
    }.bind(this))
  }

  DuplexStream.call(this)
}

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}

this._callback(err)
        this._callback = null
      }
    }.bind(this)

    this.on('pipe', function onPipe (src) {
      src.on('error', piper)
    })
    this.on('unpipe', function onUnpipe (src) {
      src.removeListener('error', piper)
    })
  } else {
    this.append(callback)
  }

  DuplexStream.call(this)
}