code: protected int getArg0AsNode(XPathContext xctxt)
            throws javax.xml.transform.TransformerException
    {
  
      return (null == m_arg0)
             ? xctxt.getCurrentNode() : m_arg0.asNode(xctxt);
    }
docs: Execute the first argument expression that is expected to return a
  nodeset.  If the argument is null, then return the current context node.
  
  @param xctxt Runtime XPath context.
  
  @return The first node of the executed nodeset, or the current context
  node if the first argument is null.
  
  @throws javax.xml.transform.TransformerException if an error occurs while
  executing the argument expression.