public function group($class, array $buttons, $form = '')
    {
        $attributes = array('class' => $this->prefixClasses('btn-group', array('xs', 'sm', 'lg', 'justified', 'vertical'), $class));
        if ($form == 'checkbox' || $form == 'radio') {
            $attributes['data-toggle'] = 'buttons-'.$form;
        }
        if (strpos($class, 'justified') !== false) {
            $buttons = '<div class="btn-group" role="group">'.implode('</div><div class="btn-group" role="group">', $buttons).'</div>';
        } else {
            $buttons = implode('', $buttons);
        }
        $attributes['role'] = 'group';

        return $this->page->tag('div', $attributes, $buttons);
    }