anchor.diff:  class RouteEvent {
     final String path;
     final Map parameters;
  +  final Route route;
     var _allowLeaveFutures = <Future<bool>>[];
   
  -  RouteEvent(this.path, this.parameters);
  +  RouteEvent(this.path, this.parameters, this.route);
   
     /**
      * Can be called on leave with the future which will complete with a boolean
  
positive.code:         return _processNewRoute(baseRoute, path, match, matchedRoute);
        } else {
          baseRoute._currentRoute._lastEvent =
              new RouteEvent(match.match, match.parameters);
          return route(match.tail, startingFrom: matchedRoute);
        }
      }
  
negative.code:     _allowLeaveFutures.add(allow);
    }
  
    RouteEvent _clone() => new RouteEvent(path, parameters, route);
  }
  
  abstract class Routable {
  