anchor.diff:      negatable: false,
       abbr: 'h',
       help: 'Prints help output.',
  +  )
  +  ..addOption(
  +    argHost,
  +    defaultsTo: 'localhost',
  +    help: 'Hostname to serve DevTools on.',
     )
     ..addOption(
       argPort,
  
positive.code: const argDebugMode = 'debug';
  const argLaunchBrowser = 'launch-browser';
  const argMachine = 'machine';
  const argPort = 'port';
  const argProfileMemory = 'profile-memory';
  const argTryPorts = 'try-ports';
  
negative.code:   final numPortsToTry =
        args[argTryPorts] != null ? int.tryParse(args[argTryPorts]) ?? 1 : 1;
    final bool verboseMode = args[argVerbose];
    final String hostname = args[argHost];
  
    // Support collecting profile data.
    final String vmUri = args[argVmUri];
  