public function render() {
        $rendered = '';
        foreach ($this->elements as $element) {
            if (!method_exists($this, 'openTag')) {
                $element->name = $this->multiple ?
                        $element->name . '[]' :
                        $this->getName() . '[' . $element->name . ']';

                $element->parent = $this->getName();
            }
            $rendered .= $element->render();
        }
        return $rendered;
    }