anchor.diff:  
   class _EventSource {
     final Uri url;
  +  final String auth;
   
     http.StreamedResponse _response;
     http.Client _client;
   
     StreamController<_Event> _controller;
   
  -  _EventSource(String url, {bool withCredentials: false})
  +  _EventSource(String url, {bool withCredentials: false, this.auth})
         : this.url = Uri.parse(url) {
   
       _controller = new StreamController(
  
positive.code: 
    _FirebaseSubscription(Firebase ref) {
      _current = new DataSnapshot._(ref, null);
      _source = new _EventSource(ref.url.toString());
  
      StreamSubscription subscription;
  
  
negative.code:   }
  
    Future _open() async {
      var request = new http.Request("GET", url.resolve(".json")
          .replace(queryParameters: auth!=null ? {"auth": auth} : const {}));
      request.headers["Accept"] = "text/event-stream";
      _client = new http.Client();
  
  