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:     browserPath = _dartiumPath();
    }
  
    if (results['chrome']) {
      appPath = 'build/deploy-test-out/web';
      browserPath = _chromePath();
    }
  
    if (results['appPath'] != null) {
  
negative.code:   if (FileSystemEntity.isFileSync(path)) {
      return new File(path).absolute.path;
    } else {
      throw 'unable to locate Dartium (${path})';
    }
  }
  
  String _chromeStablePath() {
    if (Platform.isLinux) {
      return '/usr/bin/google-chrome';
    } else if (Platform.isMacOS) {
      return '/Applications/Google Chrome.app/Contents/MacOS/Google Chrome';
    } else {
      // TODO: locate Chrome on Windows
      throw 'unable to locate Chrome; ${Platform.operatingSystem} not yet supported';
    }
  }
  
  String _chromeDevPath() {
    if (Platform.isLinux) {
      return '/usr/bin/google-chrome-unstable';
    } else {
      // TODO:
      throw 'unable to locate Chrome dev; ${Platform.operatingSystem} not yet supported';
    }
  }
  
  