code: public function execute(InputInterface $input, OutputInterface $output)
      {
          parent::execute($input, $output);
  
          $services = $this->registry->getServices();
  
          $actions = array();
  
          foreach ($services as $service) {
              foreach ($service->getGroups() as $group) {
                  foreach ($group->getActions() as $action) {
                      $actions[] = array(
                          $service->getName(),
                          $group->getName(),
                          $action->getName(),
                      );
                  }
              }
          }
  
          $table = new Table($output);
  
          $table->setHeaders(array('Service', 'Group', 'Action'))
              ->setRows($actions);
  
          $table->render();
      }
docs: {@inheritdoc}