code: public  NodeIterator selectNodeIterator(
            Node contextNode, String str, Node namespaceNode)
              throws TransformerException
    {
  
      // Execute the XPath, and have it return the result
      XObject list = eval(contextNode, str, namespaceNode);
  
      // Have the XObject return its result as a NodeSetDTM.                
      return list.nodeset();
    }
docs: Use an XPath string to select a nodelist.
  XPath namespace prefixes are resolved from the namespaceNode.
  
  @param contextNode The node to start searching from.
  @param str A valid XPath string.
  @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
  @return A NodeIterator, should never be null.
  
  @throws TransformerException