anchor.diff:    print('valid options:');
     print(parser.getUsage().replaceAll('\n\n', '\n'));
     print('');
  -  print('Generally, you should run this tool with either --dartium or --chrome. Optionally, you');
  -  print('can specify the browser to run the app in, and the application directory to launch.');
  +  print('Generally, you should run this tool with either --dartium or --chrome-*.');
  +  print('Optionally, you can specify the browser to run the app in, and the application');
  +  print('directory to launch.');
   }
   
   String _dartiumPath() {
  
positive.code:   if (FileSystemEntity.isFileSync(path)) {
      return new File(path).absolute.path;
    } else {
      throw 'unable to locate path to chrome (${path})';
    }
  }
  
  String _chromePath() {
    if (Platform.isLinux) {
      return '/usr/bin/google-chrome';
    } else if (Platform.isMacOS) {
      return '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';
    } else {
      throw 'unable to locate path to chrome';
    }
  }
  
  
negative.code:   parser.addFlag('dartium',
        help: 'run in dartium, test the app in app/', negatable: false);
    parser.addFlag('chrome',
        help: 'an alias to --chrome-stable', negatable: false);
    parser.addFlag('chrome-stable',
        help: 'run in chrome stable, test the app in build/deploy-test-out/web/', negatable: false);
    parser.addFlag('chrome-dev',
        help: 'run in chrome dev, test the app in build/deploy-test-out/web/', negatable: false);
  
    parser.addOption('appPath', help: 'the application path to run');
    parser.addOption('browserPath', help: 'the path to chrome');
  