protected function filter_slug($value, $params = null)
    {
        $delimiter = '-';
        $slug = strtolower(trim(preg_replace('/[\s-]+/', $delimiter, preg_replace('/[^A-Za-z0-9-]+/', $delimiter, preg_replace('/[&]/', 'and', preg_replace('/[\']/', '', iconv('UTF-8', 'ASCII//TRANSLIT', $str))))), $delimiter));
        return $slug;
    }