code: public function queryGroupBy($byColumn, bool $removeColumn = false): Map
  	{
  		return $this->selector->groupBy($this->getSelect(), $byColumn, $removeColumn);
  	}
docs: Return array where each value is an array of rows grouped by a single column.
  @param string|int $byColumn Column to group by.
  @param bool $removeColumn If set to true, the group by column is removed from the row.
  @return Map