code: public function load(array $configs, ContainerBuilder $container)
      {
          $loader = new Loader\YamlFileLoader($container, new FileLocator(dirname(__DIR__) . '/Resources/config'));
          $loader->load('services.yaml');
  
          $twigFilesystemLoaderDefinition = $container->getDefinition('twig.loader.filesystem');
          // register themes as Twig namespaces
          foreach ($container->getParameter('kernel.themes') as $namespace => $class) {
              /** @var ThemeInterface $themeClass */
              $themeClass = new $class();
              $twigFilesystemLoaderDefinition->addMethodCall('addPath', [$themeClass->getPath(), $namespace]);
          }
      }
docs: Loads a specific configuration.
  
  @param array            $configs   An array of configuration values
  @param ContainerBuilder $container A ContainerBuilder instance
  
  @throws InvalidArgumentException When provided tag is not defined in this extension
  @throws Exception