return NullValue.NULL;
return null;
  public static Value tmpfile(Env env)  {    try {      // XXX: remove on exit      // XXX: location of tmp files s/b configurable      Path tmp = env.getPwd().lookup("/tmp");      tmp.mkdirs();      Path file = tmp.createTempFile("resin", "tmp");      return new FileWriteValue(file);    } catch (IOException e) {      log.log(Level.FINE, e.toString(), e);      return NullValue.NULL;    }  }