anchor.diff:    Stream<T> toStream() => _controller.stream;
   
     @override
  -  String toString() => 'Signal(${_hasInitialized ? _value : "Uninitialized"})';
  +  String toString() => 'Signal($_value)';
   }
   
   class _ConstantSignal<T> implements Signal<T> {
  
positive.code:   @override
    set value(T newValue) {
      if (newValue != null && newValue != _value) {
        _hasInitialized = true;
        _value = newValue;
        _controller.add(_value);
      }
    }
  
    @override
    bool get isHot => _hasInitialized == true;
  
    @override
    bool get isCold => _hasInitialized == false;
  
    @override
    StreamSubscription onChange(void f(T newValue), {bool ignoreFirst: false}) {
      if (_hasInitialized && !ignoreFirst) {
        f(_value);
      }
      return _controller.stream.listen(f);
  
negative.code: class _SyncSignalRef<T> implements SignalRef<T> {
    final _controller = new StreamController<T>.broadcast(sync: true);
  
    T _value;
  
    _SyncSignalRef._(this._value);
  
    @override
    T get value => _value;
  