code: public String dump() {
  
          try {
              Document doc = Node.dumpTree(m_root);
              OutputFormat outformat = OutputFormat.createPrettyPrint();
              ByteArrayOutputStream buffer = new ByteArrayOutputStream();
              outformat.setEncoding("UTF-8");
              XMLWriter writer = new XMLWriter(buffer, outformat);
              writer.write(doc);
              writer.flush();
              return new String(buffer.toByteArray(), "UTF-8");
          } catch (IOException e) {
              // CAn't happen
              return null;
          }
      }
docs: Dumps the tree as XML.<p>
  
  @return the tree in XML format