protected function guess_element_id($item, $element) {
        if (!$id = $element->getAttribute('id')) {
            $attributes = $element->getAttributes();
            $id = $attributes['id'] = 'feedback_item_' . $item->id;
            $element->setAttributes($attributes);
        }
        if ($element->getType() === 'group') {
            return 'fgroup_' . $id;
        }
        return 'fitem_' . $id;
    }