public function row($content)
    {
        if (!$content instanceof \Closure) {
            $row = new Row($content);
        } else {
            $row = new Row();

            call_user_func($content, $row);
        }

        ob_start();

        $row->build();

        $contents = ob_get_contents();

        ob_end_clean();

        return $this->append($contents);
    }