anchor.diff:    parser
       ..addOption(
         argTryPorts,
  -      defaultsTo: '1',
  +      defaultsTo: defaultTryPorts.toString(),
         valueHelp: 'count',
         help: 'The number of ascending ports to try binding to before failing '
             'with an error. ',
  
positive.code:   final port = args[argPort] != null ? int.tryParse(args[argPort]) ?? 0 : 0;
    final bool headlessMode = args[argHeadlessMode];
    final bool debugMode = args[argDebugMode];
    final numPortsToTry =
        args[argTryPorts] != null ? int.tryParse(args[argTryPorts]) ?? 1 : 1;
    final bool verboseMode = args[argVerbose];
    final String hostname = args[argHost];
  
  
negative.code: const argTryPorts = 'try-ports';
  const argVerbose = 'verbose';
  const launchDevToolsService = 'launchDevTools';
  
  const defaultTryPorts = 10;
  
  const errorLaunchingBrowserCode = 500;
  
  