TreeWalker walker = new TreeWalker(this);
TreeWalker walker = new TreeWalker(this, new org.apache.xpath.DOM2Helper());
  public void serialize(Node node) throws IOException  {    try    {      TreeWalker walker = new TreeWalker(this);      walker.traverse(node);    }    catch (org.xml.sax.SAXException se)    {      throw new WrappedRuntimeException(se);    }  }