anchor.diff:  /// function in BindableList.
   class ComputedMappedBindableList<T, O> extends MappedBindableList<T, O> {
       List<StreamSubscription> _subscribers = [];
  +    List<StreamSubscription> _invalidationSubscribers = [];
       List<Bindable> _mapInputs = [];
   
       /// Arguments to the map function are [mapItem, input1, input2, ...]
  
positive.code:                 this._subscribers.add(mapInput.changeStream.listen((c) {
                      this._updateMapBindable(map);
                  }));
              });
              this._updateMapBindable(map);
          }
  
negative.code:             this._mapBindable.value = mapFunction;
              this._mappedChangeStream = this._input.changeStream.map(_mapChangeRecord);
              this._inputChanges = this._mappedChangeStream.listen(_onInputChange);
              this._basisInvalidationListener = this._input.invalidationStream.listen((c) =>
                  this.invalidationController.add(true));
  
              this._mapBindable.changeStream.listen((c) {
                  this.listInstance.replaceRange(
  