anchor.diff:    Stream<ViewModel> _stream;
     ViewModel _latestValue;
     ConverterError _latestError;
  +  S _lastConvertedState;
   
     @override
     void initState() {
  
positive.code: 
    bool _ignoreChange(S state) {
      if (widget.ignoreChange != null) {
        return !widget.ignoreChange(state);
      }
  
      return true;
  
negative.code:             : widget.builder(context, _latestValue);
    }
  
    bool _stateChanged(S state) {
      var ifStateChanged = !identical(_lastConvertedState, widget.store.state);
      _lastConvertedState = widget.store.state;
      return ifStateChanged;
    }
  
    ViewModel _mapConverter(S state) {
      return widget.converter(widget.store);
    }
  