sclass FormInFlight {

  Conversation conversation;

  S hashTag;

  new L<FormStep> steps;

  int stepIndex; // in steps list

  S handleInput(S s) { null; }

  FormStep currentStep() {

    ret get(steps, stepIndex);

  }

  void update(Runnable onChange) {

    if (currentStep() != null) currentStep().update(onChange);

  }

  S complete() { ret "Form complete"; }

  S cancel() { ret "Request cancelled"; }

  FormStep byKey(S key) {

    ret objectWhere(steps, +key);

  }

  S getValue(S key) {

    FormStep step = byKey(key);

    ret step?.value;

  }

  SS allValues() {

    SS map = litorderedmap();

    for (FormStep step : steps)

      map.put(step.key, step.value);

    ret map;

  }

  bool allowGeneralOverride() { false; }

  Conversation cancelMe() {

    Conversation conv = conversation;

    print("cancelMe called");

    // TODO: conversation.cancelForm();

    ret conv;

  }

  void change {

    if (conversation != null) conversation.change();

  }

}

abstract concept BotShowForm > BotStep {

  abstract FormInFlight makeForm();

  bool run(Conversation conv) {

    Form form = makeForm();

    true;

  }