public static function get_page_items_returns() {
        return new external_single_structure(
            array(
                'items' => new external_multiple_structure(
                    feedback_item_exporter::get_read_structure()
                ),
                'hasprevpage' => new external_value(PARAM_BOOL, 'Whether is a previous page.'),
                'hasnextpage' => new external_value(PARAM_BOOL, 'Whether there are more pages.'),
                'warnings' => new external_warnings(),
            )
        );
    }