public static function launch_attempt_parameters() {
        return new external_function_parameters (
            array(
                'lessonid' => new external_value(PARAM_INT, 'lesson instance id'),
                'password' => new external_value(PARAM_RAW, 'optional password (the lesson may be protected)', VALUE_DEFAULT, ''),
                'pageid' => new external_value(PARAM_INT, 'page id to continue from (only when continuing an attempt)', VALUE_DEFAULT, 0),
                'review' => new external_value(PARAM_BOOL, 'if we want to review just after finishing', VALUE_DEFAULT, false),
            )
        );
    }