anchor.diff:      'help',
       abbr: 'h',
       help: 'Print this help message.',
  +    negatable: false,
  +  );
  +  parser.addOption(
  +    'mapDir',
  +    help: 'The absolute path of the directory to which the relevance data will '
  +        'be written. Using this option will prevent the relevance table from '
  +        'being written.',
  +  );
  +  parser.addOption(
  +    'reduceDir',
  +    help: 'The absolute path of the directory from which the relevance data '
  +        'will be read.',
     );
     parser.addFlag(
       'verbose',
  
positive.code:   if (result.wasParsed('help')) {
      printUsage(parser);
      return false;
    } else if (result.rest.length != 1) {
      printUsage(parser, error: 'No package path specified.');
      return false;
    }
    var rootPath = result.rest[0];
    if (!PhysicalResourceProvider.INSTANCE.pathContext.isAbsolute(rootPath)) {
      printUsage(parser, error: 'The package path must be an absolute path.');
      return false;
    }
    if (!io.Directory(rootPath).existsSync()) {
      printUsage(parser, error: 'The directory "$rootPath" does not exist.');
      return false;
    }
    return true;
  
negative.code:   var result = parser.parse(args);
  
    if (validArguments(parser, result)) {
      var provider = PhysicalResourceProvider.INSTANCE;
      var packageRoot = provider.pathContext.normalize(package_root.packageRoot);
      var generatedFilePath = provider.pathContext.join(
  