RationalEgoism

void main() {
  var streamController = StreamController<int>.broadcast();

  streamController.stream
      .where((event) => event % 2 == 0)
      .listen((event) => print('First sub for odd number: $event'));

  streamController.stream
      .map((event) => event * event)
      .listen((event) => print('Second sub square number: $event'));

RationalEgoism

void main() {
  var streamController = StreamController();
  streamController.stream.listen((event) {
    print(event);
  });
  // Runtime error  Bad state: Stream has already been listened to.
  // streamController.stream.listen((event) {
  //   print('Second subscription: $event');
  // });
  streamController.sink.add('dddd');