anchor.diff:    /// Attempt to start a new connection.
     Future _start() async {
       _readyState = EventSourceReadyState.CONNECTING;
  -    var request = new http.Request("GET", url);
  +    var request = new http.Request(_method, url);
       request.headers["Cache-Control"] = "no-cache";
       request.headers["Accept"] = "text/event-stream";
       if (_lastEventId.isNotEmpty) {
  
positive.code:   Duration _retryDelay = const Duration(milliseconds: 3000);
    String _lastEventId;
    EventSourceDecoder _decoder;
  
    /// Create a new EventSource by connecting to the specified url.
    static Future<EventSource> connect(url,
        {http.Client client, String lastEventId, Map headers}) async {
      // parameter initialization
      url = url is Uri ? url : Uri.parse(url);
      client = client ?? new http.Client();
      lastEventId = lastEventId ?? "";
      EventSource es = new EventSource._internal(url, client, lastEventId, headers);
      await es._start();
      return es;
    }
  
    EventSource._internal(this.url, this.client, this._lastEventId, this.headers) {
      _decoder = new EventSourceDecoder(retryIndicator: _updateRetryDelay);
    }
  
  
negative.code:         request.headers[k] = v;
        }); 
      }
      if (_body == null) {
        request.body = '';
      } else {
        request.body = json.encode(_body);
      }
  
      var response = await client.send(request);
      if (response.statusCode != 200) {
        // server returned an error
  