/// one style of writing
String messageReducer(String msg, Action action) {
  if (action.type == 'shared') {
    return '$msg [shared]';
  }
  return msg;
}

class MessageComponent extends Component<String> {
    MessageComponent(): super(
            view: buildMessageView,
            effect: buildEffect(),
            reducer: messageReducer,
        );
}

/// another style of writing
Reducer<String> buildMessageReducer() {
  return asReducer(<Object, Reducer<String>>{
    'shared': _shared,
  });
}

String _shared(String msg, Action action) {
  return '$msg [shared]';
}

class MessageComponent extends Component<String> {
    MessageComponent(): super(
            view: buildMessageView,
            effect: buildEffect(),
            reducer: buildMessageReducer(),
        );
}