protected function selectmultiple_controls(structure $structure) {
        $output = '';

        // Bulk action button delete and bulk action button cancel.
        $buttondeleteoptions = array(
            'type' => 'button',
            'id' => 'selectmultipledeletecommand',
            'value' => get_string('deleteselected', 'mod_quiz'),
            'class' => 'btn btn-secondary'
        );
        $buttoncanceloptions = array(
            'type' => 'button',
            'id' => 'selectmultiplecancelcommand',
            'value' => get_string('cancel', 'moodle'),
            'class' => 'btn btn-secondary'
        );

        $groupoptions = array(
            'class' => 'btn-group selectmultiplecommand actions',
            'role' => 'group'
        );

        $output .= html_writer::tag('div',
                        html_writer::tag('button', get_string('deleteselected', 'mod_quiz'), $buttondeleteoptions) .
                        " " .
                        html_writer::tag('button', get_string('cancel', 'moodle'),
                $buttoncanceloptions), $groupoptions);

        $toolbaroptions = array(
            'class' => 'btn-toolbar',
            'role' => 'toolbar',
            'aria-label' => get_string('selectmultipletoolbar', 'quiz'),
        );

        // Select all/deselect all questions.
        $buttonselectalloptions = array(
            'role' => 'button',
            'id' => 'questionselectall',
            'class' => 'btn btn-link'
        );
        $buttondeselectalloptions = array(
            'role' => 'button',
            'id' => 'questiondeselectall',
            'class' => 'btn btn-link'
        );
        $output .= html_writer::tag('div',
                html_writer::tag('div',
                        html_writer::link('#', get_string('selectall', 'quiz'), $buttonselectalloptions) .
                        html_writer::tag('span', "/", ['class' => 'separator']) .
                        html_writer::link('#', get_string('selectnone', 'quiz'), $buttondeselectalloptions),
                        array('class' => 'btn-group selectmultiplecommandbuttons')),
                $toolbaroptions);
        return $output;
    }