How to modify a constructor in an existing class within a namespace

[tacman]

I see how to modify a class: https://github.com/nette/php-generator?tab=readme-ov-file#generating-from-existing-ones

But I'm missing how to modify an entire namespace, and in particular, and struggling how to copy the use statement.

I feel like I'm missing something simple. For example, I want to inject

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;

final class TestController extends AbstractController
{
}

I want to inject an entity manager

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Routing\Attribute\Route;
use Doctrine\ORM\EntityManagerInterface;

final class TestController extends AbstractController
{
    public function __construct(private EntityManagerInterface $em) {
    }

}

I understand how to create this file with PhpGenerator alone and how to load the class with existing bodies, per the instructions above. But how do I get the PhpNamespace instance, so I can tweak the methods and generate the class with the uses and everything else?

Thanks.