static private function getDriver() {
        if (self::$_driver != null) return self::$_driver;
        
        $driver = Utils::spare(Config::get('session.driver'), 'default');

        switch (strtolower($driver)) {
            case 'cookie':
                self::$_driver = new \Lollipop\Session\Cookie();
                break;
                
            case 'default':
            default:
                self::$_driver = new \Lollipop\Session\Session();
                break;
        }
        
        return self::$_driver;
    }