anchor.diff:  
   abstract class Transport {
     Future<Uint8List> transport(Uint8List request, Context context);
  +  Future<void> abort();
   }
   
   abstract class TransportCreator<T extends Transport> {
  
positive.code:   }
  
    Future<T> invoke<T>(String fullname,
        {List args = null, ClientContext context = null}) async {
      if (context == null) context = new ClientContext();
      context.init(this, T);
      if (args == null) args = [];
  
negative.code:   Transport operator [](String name) => _transports[name];
    final Map<String, dynamic> requestHeaders = {};
    ClientCodec codec = DefaultClientCodec.instance;
    Duration timeout = new Duration(seconds: 30);
    List<Uri> _urilist = [];
    List<Uri> get uris => _urilist;
    set uris(List<Uri> value) {
  