in zephir the form's getMessagesFor can not call

        class Test extends \Phalcon\Forms\Form
        {
                  public function test()
                  {
                          var messages,message,element;

                          for element in this->getElements()
                          {

                              let messages = this->getMessagesFor(element->getName());
                              messages->rewind();
                              while messages->valid()
                              {
                                  let message = messages->current();
                                  this->{"flash"}->message("error",message);
                                  messages->next();
                              }
                    }         
        }

let messages = this->getMessagesFor(element->getName());

can not execute. I can't find source. It's not any decription.