public function register(Application $app)
 {
     $app->singleton('session', function () use($app) {
         /** @var SessionHandler $handler */
         $handler = null;
         $container = $app->getContainer();
         if ($container->exists('session.handler')) {
             $handler = $container->make('session.handler');
         }
         return new Session(new NativeSessionStorage($app->getParameter('session.options', []), $handler));
     });
 }