public static function get_potential_users_parameters() {
        return new external_function_parameters(
            array(
                'courseid' => new external_value(PARAM_INT, 'course id'),
                'enrolid' => new external_value(PARAM_INT, 'enrolment id'),
                'search' => new external_value(PARAM_RAW, 'query'),
                'searchanywhere' => new external_value(PARAM_BOOL, 'find a match anywhere, or only at the beginning'),
                'page' => new external_value(PARAM_INT, 'Page number'),
                'perpage' => new external_value(PARAM_INT, 'Number per page'),
            )
        );
    }