anchor.diff:  import 'logic.dart';
   
   class PrivateAction extends Action {
  -  final Object current;
  -  PrivateAction(Object type, {dynamic payload, this.current})
  +  final Object target;
  +  PrivateAction(Object type, {dynamic payload, this.target})
         : super(type, payload: payload);
   
     Action asAction() => Action(type, payload: payload);
  
positive.code:         action = PrivateAction(
            action.type,
            payload: action.payload,
            current: ctx.state,
          );
        }
        superDispatch(action);
  
negative.code:     final Reducer<T> superReducer = super.privateReducer;
      return superReducer != null
          ? (T state, Action action) {
              if (action is PrivateAction && action.target == state) {
                return superReducer(state, action.asAction());
              }
              return state;
  