code: public  NodeIterator selectNodeIterator(Node contextNode, String str)
            throws TransformerException
    {
      return selectNodeIterator(contextNode, str, contextNode);
    }
docs: Use an XPath string to select a nodelist.
  XPath namespace prefixes are resolved from the contextNode.
  
  @param contextNode The node to start searching from.
  @param str A valid XPath string.
  @return A NodeIterator, should never be null.
  
  @throws TransformerException