public static function get_questions_attempts_parameters() {
        return new external_function_parameters (
            array(
                'lessonid' => new external_value(PARAM_INT, 'lesson instance id'),
                'attempt' => new external_value(PARAM_INT, 'lesson attempt number'),
                'correct' => new external_value(PARAM_BOOL, 'only fetch correct attempts', VALUE_DEFAULT, false),
                'pageid' => new external_value(PARAM_INT, 'only fetch attempts at the given page', VALUE_DEFAULT, null),
                'userid' => new external_value(PARAM_INT, 'only fetch attempts of the given user', VALUE_DEFAULT, null),
            )
        );
    }