SassList::index PHP Метод

    public function index($value)
    {
        for ($i = 0; $i < count($this->value); $i++) {
            if (trim((string) $value) == trim((string) $this->value[$i])) {
                return new SassNumber($i);
            }
        }
        return new SassBoolean(false);
    }

 public static function index($list, $value)
 {
     if (!$list instanceof SassList) {
         $list = new SassList($list->toString());
     }
     return $list->index($value);
 }