anchor.diff:  class MappedBindableList<T, O> extends FixedBindableList<T> {
       Stream<ChangeRecord> _mappedChangeStream;
       StreamSubscription<ChangeRecord> _inputChanges;
  +    StreamSubscription _basisInvalidationListener;
       final BaseBindableList<O> _input;
       Bindable<Function> _mapBindable = new Bindable((c) => null);
   
  
positive.code:             this._mapBindable.value = mapFunction;
              this._mappedChangeStream = this._input.changeStream.map(_mapChangeRecord);
              this._inputChanges = this._mappedChangeStream.listen(_onInputChange);
  
              this._mapBindable.changeStream.listen((c) {
                  this.listInstance.replaceRange(
  
negative.code: /// 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, ...]
  