public function filter($value)
        {
            // transliteration
            $value = strtr($value, $this->transliteration);

            // change to lowercase
            if($this->transformCase) {
                $value = mb_convert_case($value, MB_CASE_LOWER, 'utf8');
            }

            // replace punctuation
            if($this->transformPunctuation) {
                $value = strtr($value, $this->punctuation);
            }

            return $value;
        }