public static function get_blocked_users_returns() {
        return new external_single_structure(
            array(
                'users' => new external_multiple_structure(
                    new external_single_structure(
                        array(
                            'id' => new external_value(PARAM_INT, 'User ID'),
                            'fullname' => new external_value(PARAM_NOTAGS, 'User full name'),
                            'profileimageurl' => new external_value(PARAM_URL, 'User picture URL', VALUE_OPTIONAL)
                        )
                    ),
                    'List of blocked users'
                ),
                'warnings' => new external_warnings()
            )
        );
    }