main.dart

void main() async {
  // Iterate only over the first 5 items
  await for (final value in counter().take(5)) {
    print('$value');
  }
}

// Emits an incrementing value every seconds
Stream<int> counter() async* {
  print('start');

  try {
    var i = 0;
    // While we have an infinite loop, the loop will be
    // executed only for the first 5 items
    while (true) {
      yield i++;
      await Future.delayed(Duration(seconds: 1));
    }
  } finally {
    // The finally clause is properly reached when
    // we stop using the Stream<int>
    print('end');
  }
}