code: public function innerHTML()
      {
          $dom = dom_import_simplexml($this);
          $doc = $dom->ownerDocument;
  
          $html = '';
          foreach ($dom->childNodes as $child) {
              $html .= ($child instanceof DOMText) ? $child->textContent : $doc->saveXML($child);
          }
  
          return $html;
      }
docs: Return the content of current node as a string
  
  Roughly emulates the innerHTML property found in browsers, although it is not meant to
  perfectly match any specific implementation.
  
  @todo Write a test for HTML entities that can't be represented in the document's encoding
  
  @return    string            Content of current node