static int callAnswerMethod_history;

static S callAnswerMethod(S s) {
  if (callAnswerMethod_history == 0)
    callAnswerMethod_history = hasMethod(mc(), "answer", s, new L) ? 1 : -1;
  if (callAnswerMethod_history > 0)
    ret callMC("answer", s, emptyList());
  else
    ret callMC("answer", s);
}

static S callAnswerMethod(O responder, S s) {
  ret callAnswerMethod(responder, s, litlist(s));
}

static S callAnswerMethod(O responder, S s, L<S> history) {
  S answer = (S) callOpt(responder, "answer", s, history);
  if (answer == null)
    answer = (S) callOpt(responder, "answer", s);
  return emptyToNull(answer);
}