/**
  * Dumps the internal XML tree back into a string with added whitespace 
  * (new-lines and tabbing).
  * 
  * @param optional object DOMNode $node
  * @param optional int $options
  * @return string
  * @access public
  * @since 1/23/08
  */
 public function saveXMLWithWhitespace(DOMNode $node = null, $options = null)
 {
     $doc = new Harmoni_DOMDocument();
     if (is_null($node)) {
         if ($this->documentElement) {
             $doc->appendChild($doc->importNode($this->documentElement, true));
         }
     } else {
         $doc->appendChild($doc->importNode($node, true));
     }
     $doc->addWhitespaceToDocument();
     return $doc->saveXML($doc->documentElement, $options);
 }