anchor.diff:        help: 'Prints help and usage information.',
         negatable: false,
         callback: (help) {
  -        if (help) {
  -          print(parser.getUsage());
  -          print('Usage: dart docgen.dart [OPTIONS] fooDir/barFile');
  -          exit(0);
  -        }
  +        if (help) _printHelpAndExit();
         });
     parser.addFlag('verbose', abbr: 'v',
         help: 'Output more logging information.', negatable: false,
  
positive.code:   var includeSdk = results['parse-sdk'] || results['include-sdk'];
    var scriptDir = path.dirname(Platform.script.toFilePath());
    var introduction = includeSdk ? '' : results['introduction'];
    docgen(results.rest.map(path.normalize).toList(),
        packageRoot: results['package-root'],
        outputToYaml: !results['json'],
        includePrivate: results['include-private'],
  
negative.code: }
  
  /**
   * Print help if we are passed the help option or invalid arguments.
   */
  void _printHelpAndExit() {
    print(_initArgParser().getUsage());
    print('Usage: dart docgen.dart [OPTIONS] fooDir/barFile');
    exit(0);
  }
  
  /**
   * Creates parser for docgen command line arguments.
   */
  ArgParser _initArgParser() {
  