code: public function toNode(DOMDocument $document = null)
      {
          if (null === $document) {
              $document = new DOMDocument();
          }
  
          $node = $document->createElement('POA');
  
          $code = $this->getCode();
          if (isset($code)) {
              $node->appendChild($document->createElement('Code', $code));
          }
  
          $description = $this->getDescription();
          if (isset($description)) {
              $node->appendChild($document->createElement('Description', $description));
          }
  
          return $node;
      }
docs: @param null|DOMDocument $document
  
  @return DOMElement