code: def add_users(self, category):
          
          mapping = {'banned': 'ban', 'contributor': 'make_contributor',
                     'moderator': 'make_moderator'}
  
          if category not in mapping:
              print('{!r} is not a valid option for --add'.format(category))
              return
          func = getattr(self.sub, mapping[category])
          print('Enter user names (any separation should suffice):')
          data = sys.stdin.read().strip()
          for name in re.split('[^A-Za-z0-9_]+', data):
              func(name)
              print('Added {!r} to {}'.format(name, category))
docs: Add users to 'banned', 'contributor', or 'moderator'.