anchor.diff:        }
         if (content == null)
           continue;
  -      String key = historyEntry.route.key;
         Transition transition = new Transition(
  -        key: key,
  +        key: historyEntry.key.toString(),
           content: content,
           direction: (i <= state.historyIndex) ? TransitionDirection.forward : TransitionDirection.reverse,
           interactive: (i == state.historyIndex),
  
positive.code:       if (route.name != null)
          namedRoutes[route.name] = route;
      }
      history.add(new HistoryEntry(routes[0]));
    }
  
    List<HistoryEntry> history = new List<HistoryEntry>();
    int historyIndex = 0;
    Map<String, RouteBase> namedRoutes = new Map<String, RouteBase>();
  
    RouteBase get currentRoute => history[historyIndex].route;
  
negative.code:   }
  
    void push(RouteBase route) {
      HistoryEntry historyEntry = new HistoryEntry(route: route, key: _lastKey++);
      history.insert(historyIndex + 1, historyEntry);
      historyIndex++;
    }
  