public mod parseInteractive() {
   mod tree = null;
   PythonParser parser = setupParser(true);
   try {
     PythonParser.single_input_return r = parser.single_input();
     tree = (mod) r.tree;
   } catch (RecognitionException e) {
     // I am only throwing ParseExceptions, but "throws RecognitionException" still gets
     // into the generated code.
     System.err.println("FIXME: pretty sure this can't happen -- but needs to be checked");
   }
   return tree;
 }