public static function clean($request = null)
    {
        switch ($request) {
            case 'post':
                unset($_POST);
            break;

            case 'get':
                unset($_GET);
            break;

            case 'any':
                unset($_REQUEST);
            break;

            default:
                unset($_POST);
                unset($_REQUEST);
                unset($_GET);
        }
    }