Medusa\Stack\PersistentStack::createEmpty PHP Метод

    public static function createEmpty()
    {
        return new EmptyStack();
    }

 private function reversedBackwards()
 {
     $s = PersistentStack::createEmpty();
     foreach ($this->backwards as $value) {
         $s = $s->push($value);
     }
     return $s;
 }