Bluz\Grid\Grid::checkFilter PHP Method

    public function checkFilter($filter)
    {
        if ($filter == self::FILTER_EQ || $filter == self::FILTER_NE || $filter == self::FILTER_GT || $filter == self::FILTER_GE || $filter == self::FILTER_LT || $filter == self::FILTER_LE || $filter == self::FILTER_NUM || $filter == self::FILTER_ENUM || $filter == self::FILTER_LIKE) {
            return true;
        }
        return false;
    }