static S pcallAnswerMethod(S s) {
  try {
    ret callAnswerMethod(s);
  } catch e {
    printStackTrace(e);
    ret "ERROR: " + e;
  }
}

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

static S pcallAnswerMethod(O responder, S s, L<S> history) {
  try {
    ret callAnswerMethod(responder, s, history);
  } catch e {
    printStackTrace(e);
    ret "ERROR: " + e;
  }
}