code: function _pipe(out, callback, err, iresult) {
    if (err) return callback(err);
    out(iresult, callback);
  }
docs: Used to pipe input operation to output operation.
  @param {Function} out - Output operation.
  @param {Function} callback - Callback that expects only
  a possible error.
  @param {*} err - Possible error passed by caller.
  @param {Object} iresult - Result of the input operation.