protected function section_hidden($sectionno, $courseorid = null) {
        if ($courseorid) {
            $sectionname = get_section_name($courseorid, $sectionno);
            $strnotavailable = get_string('notavailablecourse', '', $sectionname);
        } else {
            $strnotavailable = get_string('notavailable');
        }

        $o = '';
        $o.= html_writer::start_tag('li', array('id' => 'section-'.$sectionno, 'class' => 'section main clearfix hidden'));
        $o.= html_writer::tag('div', '', array('class' => 'left side'));
        $o.= html_writer::tag('div', '', array('class' => 'right side'));
        $o.= html_writer::start_tag('div', array('class' => 'content'));
        $o.= html_writer::tag('div', $strnotavailable);
        $o.= html_writer::end_tag('div');
        $o.= html_writer::end_tag('li');
        return $o;
    }