// not a very good one
sbool instanceOf(O o, S className) {
  if (o == null) false;
  S c = o.getClass().getName();
  ret eq(c, className) || eq(c, "main$" + className);
}

// better
sbool instanceOf(O o, Class c) {
  if (c == null) false;
  ret c.isInstance(o);
}

sbool instanceOf(Class c, O o) {
  ret instanceOf(o, c);
}