anchor.diff:    final Router _parent;
     _Route _defaultRoute;
     _Route _currentRoute;
  -  String _lastPath;
   
     Stream<RouteEvent> get onRoute => _onRouteController.stream;
     Stream<RouteEvent> get onLeave => _onLeaveController.stream;
  
positive.code:     return new Future.value(false);
    }
    
    reroute() {
      if (_lastPath == null) {
        throw new StateError('Cannot reroute, was never routed before.');
      }
      route(_lastPath);
    }
  
    Future go(String routePath, Map parameters, {bool replace: false}) {
      var newTail = _getTailUrl(routePath, parameters);
      String newUrl = _getHead(newTail);
  
negative.code:       _defaultRoute = route;
      }
      _routes[name] = route;
    }
  
    /**
  