anchor.diff:    print("Stop scheduling");
   }
   
  +void updateStream(int movementInterval) {
  +  print("Setting movementInterval to ${movementInterval}.");
  +
  +  stream = new Stream.periodic(new Duration(milliseconds: movementInterval),
  +       movement);
  +  stream.listen((ignorethis) {}, cancelOnError: true);
  +}
  +
   
   void startUpdates(final int movementInterval, final int tailIncreaseInterval) {
  -
  -  stream = new Stream.periodic(new Duration(milliseconds: movementInterval),
  -      movement);
  -  stream.listen((ignorethis) {}, cancelOnError: true);
  +  updateStream(movementInterval);
   
     stream2 = new Stream.periodic(new Duration(milliseconds: tailIncreaseInterval
         ), increaseTailLength);
  
positive.code: 
  Random rand = new Random(47);
  
  void randomDirection() {
    int dir = rand.nextInt(4);
    switch (dir) {
      case 0:
  
negative.code: void increaseTailLength(param) {
    snake.maxSize += 1;
    pauseInMillis = max(pauseInMillis - 2, 350);
    updateStream(pauseInMillis);
  }
  
  
  