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