protected function definition_list(array $items, array $attributes = array()) {
        $output = html_writer::start_tag('dl', $attributes);
        foreach ($items as $label => $value) {
            $output .= html_writer::tag('dt', $label);
            $output .= html_writer::tag('dd', $value);
        }
        $output .= html_writer::end_tag('dl');
        return $output;
    }