anchor.diff:  class RequestNavigator {
     final Stream<HttpRequest> _incoming;
     final Router _router;
  -  final Map<String, StreamController<HttpRequest>> _streams = {};
  +  final Map<_ServerRoute, StreamController<HttpRequest>> _streams = {};
   
     /**
      * Contains [Route], [Filter], [Stream] triples where [Stream] has at least one handler.
      */
     final List _filters = [];
  +
  +  final _ServerRoute _defaultServerRouteId = new _ServerRoute('default', '');
   
     /**
      * Creates new RequestNavigator listening on [_incoming].
  
positive.code:   }
  
    Stream<HttpRequest> _navigateToRoute(HttpRequest req, String routeName, Map params){
      if(!_streams.containsKey(routeName)){
        throw new ArgumentError("Stream not found for '$routeName'");
      }
  
      var streamController = _streams[routeName];
      streamController.add(req);
      return streamController.stream;
    }
  
negative.code: // file.
  
  //TODO How we should handle uri parameters?
  //TODO   (sub of previous) should handler be an abstract class / interface?
  //TODO Futures
  
  library vacuum.router;
  import "dart:core";
  import 'dart:io';
  import 'dart:async';
  import 'router.dart';
  
  class _ServerRoute{
    String routeName;
    String method;
  
    _ServerRoute(this.routeName, this.method);
  
    String toString(){
      return routeName + ":" + method;
    }
  }
  
  /**
   * [RequestNavigator] wires together [Route] matching, [Filter]ing of [HttpRequests]
  