code: public function render(MvcEvent $e)
      {
          $result = $e->getResult();
          if ($result instanceof Response) {
              return $result;
          }
  
          // Martial arguments
          $response  = $e->getResponse();
          $viewModel = $e->getViewModel();
          if (!$viewModel instanceof ViewModel) {
              return null;
          }
  
          try {
              $result = $this->getEnvironment()->render(
                  $viewModel->getTemplate() . $this->getSuffix(),
                  (array) $viewModel->getVariables()
              );
          } catch (Twig_Error_Loader $e) {
              return null;
          }
  
          $response->setContent($result);
          $e->setResult($response);
  
          return $response;
      }
docs: Render the view
  
  @param  MvcEvent $e
  @return null|Response