public static function get_submission_status_parameters() {
        return new external_function_parameters (
            array(
                'assignid' => new external_value(PARAM_INT, 'assignment instance id'),
                'userid' => new external_value(PARAM_INT, 'user id (empty for current user)', VALUE_DEFAULT, 0),
                'groupid' => new external_value(PARAM_INT, 'filter by users in group (used for generating the grading summary).
                    Empty or 0 for all groups information.', VALUE_DEFAULT, 0),
            )
        );
    }