Silex - why don't Traits work?

Question

PHP

I want to "get" the username of the user. In the doc they write:

Silex\Application\SecurityTrait adds the following shortcuts:
user: Returns the current user.
$user = $app->user();

However, adding use Silex\Application\SecurityTrait to the controller file didn't have the desired effect.
$user = $app->user() throws an error:

Fatal error: Call to undefined method Silex\Application::user() in

On php 5.4 server.
Had a similar problem with

use Application\UrlGeneratorTrait;

, but, at that time, did not attach importance to the problem.
Why?

Answer 1

And so it works?

$token = $app['security']->getToken();
if (null !== $token) {
    $user = $token->getUser();
}

Answer 2

class Application extends Silex\Application
{
    use Silex\Application\TwigTrait;
}
 
$app = new Application();
 
$app->register(new Silex\Provider\TwigServiceProvider(), array(
    'twig.path' => __DIR__ . '/../views',
));
 
$app->get('/', function () use ($app) {
    return $app->render('home.twig');
});
 
$app->run();