code: public function build(ContainerBuilder $container)
      {
          $container->addCompilerPass(new ThemeCompilerPass(), PassConfig::TYPE_BEFORE_OPTIMIZATION, - 10);
          $container->addCompilerPass(new ThemeProviderPass());
      }
docs: Builds the bundle.
  It is only ever called once when the cache is empty.
  
  @param ContainerBuilder $container