code: public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
    {
  
      int which = getArg0AsNode(xctxt);
  
      if (DTM.NULL != which)
      {
        // Note that this is a different value than in previous releases
        // of Xalan. It's sensitive to the exact encoding of the node
        // handle anyway, so fighting to maintain backward compatability
        // really didn't make sense; it may change again as we continue
        // to experiment with balancing document and node numbers within
        // that value.
        return new XString("N" + Integer.toHexString(which).toUpperCase());
      }
      else
        return XString.EMPTYSTRING;
    }
docs: Execute the function.  The function must return
  a valid object.
  @param xctxt The current execution context.
  @return A valid XObject.
  
  @throws javax.xml.transform.TransformerException