code: def print_help(self):
      
      def print_hint():
        print('Use `pants goals` to list goals.')
        print('Use `pants help` to get help.')
      if isinstance(self._help_request, VersionHelp):
        print(pants_version())
      elif isinstance(self._help_request, OptionsHelp):
        self._print_options_help()
      elif isinstance(self._help_request, GoalsHelp):
        self._print_goals_help()
      elif isinstance(self._help_request, UnknownGoalHelp):
        print('Unknown goals: {}'.format(', '.join(self._help_request.unknown_goals)))
        print_hint()
        return 1
      elif isinstance(self._help_request, NoGoalHelp):
        print('No goals specified.')
        print_hint()
        return 1
      return 0
docs: Print help to the console.
  
      :return: 0 on success, 1 on failure