code: public function render(Container $container, $layout = Form::LAYOUT_HORIZONTAL, $parameter = array())
      {
          $content = '';
  
          $content .= $container->renderPre($this->getView());
      
          if ($container instanceof ViewPartialProviderInterface) {
              return $this->getView()->partial($container->getViewPartial(), array('element' => $container));
          }
  
          if (isset($parameter['render_label']) && $parameter['render_label'] && ($label = $container->getLabel())) {
              $content .= '<div class="container-headline"><h3>' . $this->getView()->translate($label) . '</h3></div>';
          }
          foreach ($container as $element) {
              $content .= $this->renderElement($element, $layout, $parameter);
          }
  
          $content .= $container->renderPost($this->getView());
          
          return $content;
      }
docs: Renders the forms of a container.
  
  @param Container $container
  @param string $layout
  @param array $parameter
  @return string