anchor.diff:  part of bot_hop;
   
   class _HopRunner {
  +  static const String RAW_TASK_LIST_CMD = 'print_raw_task_list';
     static final ArgParser _parser = _getParser();
     final ArgResults _args;
     final _HopState _state;
  
positive.code:       final taskName = _args.rest[0];
        if(_state.hasTask(taskName)) {
          _runTask(taskName);
        } else {
          print('No task named "$taskName".');
        }
      } else {
  
negative.code:     print('Welcome to HOP');
      print('');
      print('Tasks:');
      _printRawTasks();
      // print('');
      // print(_parser.getUsage());
    }
  
    void _printRawTasks() {
      for(final t in _state.taskNames) {
        print(t);
      }
    }
  
    static ArgParser _getParser() {
      final parser = new ArgParser();
  
      // TODO: put help in a const
      // parser.addFlag('help', abbr: '?', help: 'print help text', negatable: false);
  
      // TODO: other global flag ideas
      // verbose - show a lot of output
      // trace - show stack dump on fail?
  
      return parser;
    }
  }
  