function _recursiveFilter($filter, $value)
    {
        if (is_array($value)) {
            $cleanValues = array();
            foreach ($value as $k => $v) {
                $cleanValues[$k] = $this->_recursiveFilter($filter, $v);
            }
            return $cleanValues;
        } else {
            return call_user_func($filter, $value);
        }
    }