code: function(sql, values, cb) {
      let _values, _cb;
  
      if (typeof values === 'function') {
        _cb = values;
      } else if (values !== undefined) {
        _values = values;
        _cb = cb;
      }
  
      queryPromise(sql, _values)
        .then(rows => {
          if (_cb) _cb(null, rows, rows.meta);
        })
        .catch(_cb || emptyError);
    }
docs: Execute query using text protocol with callback emit columns/data/end/error
  events to permit streaming big result-set
  
  @param sql     sql parameter Object can be used to supersede default option.
  Object must then have sql property.
  @param values  object / array of placeholder values (not mandatory)
  @param cb      callback
  @returns {Query} query