code: function _emitStatusIfDone() {
    /* jshint validthis: true */
    var status;
    if (this.read_status && this.received_status) {
      if (this.read_status.code !== constants.status.OK) {
        status = this.read_status;
      } else {
        status = this.received_status;
      }
      if (status.code === constants.status.OK) {
        this.push(null);
      } else {
        var error = common.createStatusError(status);
        this.emit('error', error);
      }
      this.emit('status', status);
    }
  }
docs: If we have both processed all incoming messages and received the status from
  the server, emit the status. Otherwise, do nothing.
  @private