public function get_html_head_contributions($page = 'all', $showall = false) {
        if ($showall) {
            $page = 'all';
        }
        $result = '';
        foreach ($this->get_slots($page) as $slot) {
            $result .= $this->quba->render_question_head_html($slot);
        }
        $result .= question_engine::initialise_js();
        return $result;
    }