use Symfony\Component\HttpKernel\Kernel; use Symfony\Component\Config\Loader\LoaderInterface; class MyKernel extends Kernel { // ... protected function configureRoutes(RouteCollectionBuilder $routes) { $routes->import('@AppBundle/Controller/', '/', 'annotation'); $routes->addPrefix('/admin', ['_locale' => 'en']); } // ... }In this example, the addPrefix method is used to add the "/admin" prefix to all URLs used in the admin section of the application. The package library used in this example is Symfony\Component\HttpKernel. This library is part of the Symfony framework and provides the basic structure for handling HTTP requests and responses in a PHP application.