src/Versatile/Search/Filter.php
public function offsetExists($indexOrColumn)
    {

        if (is_numeric($indexOrColumn)) {
            return isset($this->expressions[(int)$indexOrColumn]);
        }

        try {
            return is_int($this->indexOfColumn($indexOrColumn));
        } catch (OutOfBoundsException $e) {
            return false;
        }
    }
public function offsetExists($indexOrColumn)
    {

        if (is_numeric($indexOrColumn)) {
            return isset($this->expressions[(int)$indexOrColumn]);
        }

        try {
            return is_int($this->indexOfColumn($indexOrColumn));
        } catch (OutOfBoundsException $e) {
            return false;
        }
    }
Checks if an expression exists at position $indexOrColumn or if an
expression was added vor column $indexOrColumn

@param string|int $indexOrColumn
@return bool