public function get_values($itemnumber) {
        if ($itemnumber <= 0 || $itemnumber > $this->get_number_of_items()) {
            $a = new stdClass();
            $a->id = $this->questionid;
            $a->item = $itemnumber;
            throw new moodle_exception('cannotgetdsfordependent', 'question', '', $a);
        }

        return $this->load_values($itemnumber);
    }