anchor.diff:  
   main() {
     const ms5 = const Duration(milliseconds: 5);
  -  const halfSec = const Duration(milliseconds: 500);
  +  const twoSecs = const Duration(seconds: 2);
   
     test("stream timeout", () {
       StreamController c = new StreamController();
  
positive.code: 
    test("stream no timeout", () {
      StreamController c = new StreamController();
      Stream tos = c.stream.timeout(halfSec);
      int ctr = 0;
      tos.listen((v) {
                   expect(v, 42);
  
negative.code:       fail("Timeout not prevented by events");
        throw "ERROR";
      });
      // Start the periodic timer before we start listening to the stream.
      // This should reduce the flakiness of the test.
      int ctr = 200;  // send this many events at 5ms intervals. Then close.
      new Timer.periodic(ms5, (timer) {
        sw.reset();
  