code: public function toNode(DOMDocument $document = null)
      {
          if (null === $document) {
              $document = new DOMDocument();
          }
  
          $node = $document->createElement('HazMatPackageInformation');
  
          if ($this->isAllPackedInOneIndicator()) {
              $node->appendChild($document->createElement('AllPackedInOneIndicator'));
          }
          if ($this->isOverPackedIndicator()) {
              $node->appendChild($document->createElement('OverPackedIndicator'));
          }
          if ($this->getQValue() !== null) {
              $node->appendChild($document->createElement('QValue', $this->getQValue()));
          }
  
          return $node;
      }
docs: @param null|DOMDocument $document
  
  @return DOMElement