anchor.diff:  
     _processResponse(HttpClientResponse response, bool value) async {
       var respBody = await UTF8.decodeStream(response);
  -
  +    _releaseLock();
       try {
         respBody = JSON.decode(respBody);
       } catch (e) {}
  
positive.code:   }
  
    Future<Object> get(Uri uri, {bool value: true}) async {
      HttpClientRequest request = await client.getUrl(uri);
      _setUpRequest(request);
      return await _processResponse(await request.close(), value);
    }
  
    Future<Object> delete(Uri uri, {bool value: true}) async {
      HttpClientRequest request = await client.deleteUrl(uri);
      _setUpRequest(request);
      return await _processResponse(await request.close(), value);
  
negative.code:     request.headers.add(HttpHeaders.ACCEPT_CHARSET, UTF8.name);
      request.headers.add(HttpHeaders.CACHE_CONTROL, "no-cache");
    }
  
    Future _getLock() async {
      while (_lock != null) {
        await _lock.future;
      }
      _lock = new Completer();
    }
  
    void _releaseLock() {
      if (_lock == null) {
        throw new StateError('No lock to release');
      }
      _lock.complete();
      _lock = null;
    }
  }
  