anchor.diff:  
     Future _detectOldVersion() async {
       final pr = await _runGCloudApp(
  -      ['versions', 'list', '--service', service, '--format=value(id)'],
  -    );
  -    if (pr.exitCode != 0) {
  -      print('[ERR] Couldn\'t detect old $service version.');
  -      print(pr.stderr);
  -      return;
  -    }
  +        ['versions', 'list', '--service', service, '--format=value(id)'],
  +        'Couldn\'t detect old $service version.');
  +
       _oldVersion = pr.stdout.trim();
       if (_oldVersion.contains('\n')) {
         print('[WARN] Multiple existing versions detected: '
  
positive.code:       '--splits',
        '$newVersion=1',
      ];
      if (migrateTraffic) {
        args.add('--migrate');
      }
      args.add('-q');
      final pr = await _runGCloudApp(args);
      if (pr.exitCode != 0) {
        print('[ERR] Couldn\'t migrate traffic for $service.');
        print(pr.stderr);
        exit(1);
      }
    }
  
    Future _deleteOldVersion() async {
      if (_oldVersion == null) return;
      final pr = await _runGCloudApp(
          ['versions', 'delete', '--service', service, _oldVersion, '-q']);
      if (pr.exitCode != 0) {
        print('[ERR] Couldn\'t delete old version of $service.');
        print(pr.stderr);
        exit(1);
      }
    }
  
    Future<ProcessResult> _runGCloudApp(List<String> args) => Process.run(
        'gcloud',
        [
          '--project',
          project,
          'app',
        ]..addAll(args));
  }
  
negative.code: 
    Future _gcloudDeploy() async {
      final String yamlFile = service == 'default' ? 'app.yaml' : '$service.yaml';
      await _runGCloudApp(
          ['deploy', yamlFile, '--no-promote', '-v', newVersion, '-q'],
          'Couldn\'t deploy $service.');
    }
  
    String get baseUrl {
  