code: public function render(FormInterface $form)
      {
          if (method_exists($form, 'prepare')) {
              $form->prepare();
          }
  
          // Set form role
          if (!$form->getAttribute('role')) {
              $form->setAttribute('role', 'form');
          }
  
          $formContent = '';
  
          foreach ($form as $element) {
              /** @var $element \Zend\Form\Form */
              if ($element instanceof FieldsetInterface) {
                  /** @noinspection PhpUndefinedMethodInspection */
                  $formContent .= $this->getView()->formCollection($element);
              } else {
                  $element->setOption('_form', $form);
  
                  /** @noinspection PhpUndefinedMethodInspection */
                  $formContent .= $this->getView()->formRow($element);
              }
          }
  
          return $this->openTag($form) . $formContent . $this->closeTag();
      }
docs: Render a form from the provided form.
  
  @param FormInterface $form
  
  @return string