docs: function MongolianGridFileWriteStream(file) {
      if (file.chunkSize instanceof Long) throw new Error("Long (64bit) chunkSize unsupported")
      if (file.chunkSize <= 0) throw new Error("File has invalid chunkSize: "+file.chunkSize)
      stream.Stream.call(this)
      this.file = file
      this.writable = true
      this.encoding = 'binary'
      this._hash = crypto.createHash('md5')
      this._chunkIndex = 0
      file.length = 0
      this._chunkSize = file.chunkSize
  }