code: function(friendnum, filenum, position, data) {
    this.type = 'FileRecvChunkEvent';
    this._friendnum = friendnum;
    this._filenum = filenum;
    this._position = position;
    this._data = data;
  }
docs: Event object fired by {@class Tox}.
  Corresponds to tox_callback_file_recv_chunk(3).
  @class
  @param {Number} friendnum - Friend number
  @param {Number} filenum - File number
  @param {Number} position - Position
  @param {Buffer} data - Chunk data
  @note size is a uint64_t