anchor.diff:    )
     ..addFlag('delete-existing', defaultsTo: true);
   
  -ArgParser globalArgParser() => ArgParser()
  -  ..addCommand('download', downloadCommandArgParser())
  -  ..addCommand('run_config', runConfigCommandArgParser())
  +ArgParser _globalArgParser() => ArgParser()
  +  ..addCommand('download', _downloadCommandArgParser())
  +  ..addCommand('run_config', _runConfigCommandArgParser())
     ..addFlag('help', abbr: 'h', help: 'Displays usage information.');
   
  -ArgResults parseArguments(ArgParser parser, List<String> arguments) {
  +ArgResults _parseArguments(ArgParser parser, List<String> arguments) {
     try {
       return parser.parse(arguments);
     } on FormatException catch (e) {
  -    dieWithUsage('Error parsing arguments:\n${e.message}\n');
  +    _dieWithUsage('Error parsing arguments:\n${e.message}\n');
     }
   }
   
  -Never dieWithUsage([String? message]) {
  +Never _dieWithUsage([String? message]) {
     if (message != null) {
       print(message);
     }
  
positive.code:     case 'run_config':
        if (commandOptions.command == null ||
            !['download', 'generate'].contains(commandOptions.command!.name)) {
          dieWithUsage('The `run_config` command has only the two subcommands: '
              '`download` and `generate`.');
        }
  
  
negative.code: import 'package:args/args.dart';
  import 'package:googleapis_generator_dependency/googleapis_generator.dart';
  
  ArgParser _downloadCommandArgParser() => ArgParser()
    ..addOption('output-dir',
        abbr: 'o',
        help: 'Output directory of discovery documents.',
        defaultsTo: 'googleapis-discovery-documents');
  
  ArgParser _runConfigCommandArgParser() => ArgParser()
    ..addCommand('download')
    ..addCommand('generate')
    ..addOption(
  