SassList::toString PHP Метод

    public function toString()
    {
        $aliases = array('comma' => ',', 'space' => '');
        $this->separator = trim($this->separator);
        if (isset($aliases[$this->separator])) {
            $this->separator = $aliases[$this->separator];
        }
        return implode($this->separator . ' ', $this->getValue());
    }

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