code: public XObject getGlobalVariable(XPathContext xctxt, final int index)
            throws TransformerException
    {
  
      XObject val = _stackFrames[index];
  
      // Lazy execution of variables.
      if (val.getType() == XObject.CLASS_UNRESOLVEDVARIABLE)
        return (_stackFrames[index] = val.execute(xctxt));
  
      return val;
    }
docs: Get a global variable or parameter from the global stack frame.
  
  
  @param xctxt The XPath context, which must be passed in order to
  lazy evaluate variables.
  
  @param index Global variable index relative to the global stack
  frame bottom.
  
  @return The value of the variable.
  
  @throws TransformerException