anchor.diff:  
   class VmServiceCapabilities {
     VmServiceCapabilities(this.version);
  +
     final Version version;
   
     bool get supportsGetScripts =>
  
positive.code:   final Completer<Null> serviceAvailable = Completer();
  
    VmServiceCapabilities _serviceCapabilities;
    Future<VmServiceCapabilities> get serviceCapabilities async {
      if (_serviceCapabilities == null) {
        await serviceAvailable.future;
  
negative.code:       '_Logging',
        '_Service',
      ];
  
      await Future.wait(streamIds.map((String id) async {
        try {
          await service.streamListen(id);
        } catch (e) {
          print("Service client stream not supported: '$id'");
          print('  $e');
        }
      }));
    }
  
    void vmServiceClosed() {
  