public function render()
    {
        $this->getEventManager()->trigger(
            'formBeforeRender',
            $this,
            array(

            )
        );
        $output = parent::render();
        $this->getEventManager()->trigger(
            'formAfterRender',
            $this,
            array(
                'output' => &$output
            )
        );
        return $output;
    }