protected function processSelect($select, $context)
    {
        if ($select instanceof Aggregate) {
            $column = $this->processColumnOrSubQuery($select->column, $context);
            if ($column === $select->column) {
                return $select;
            } else {
                return new Aggregate($select->function, $column);
            }
        }

        return $this->processColumnOrSubQuery($select, $context);
    }