code: def _get_bucketing_id(self, user_id, attributes):
      
  
      attributes = attributes or {}
      bucketing_id = attributes.get(enums.ControlAttributes.BUCKETING_ID)
  
      if bucketing_id is not None:
        if isinstance(bucketing_id, string_types):
          return bucketing_id
  
        self.logger.warning('Bucketing ID attribute is not a string. Defaulted to user_id.')
  
      return user_id
docs: Helper method to determine bucketing ID for the user.
  
      Args:
        user_id: ID for user.
        attributes: Dict representing user attributes. May consist of bucketing ID to be used.
  
      Returns:
        String representing bucketing ID if it is a String type in attributes else return user ID.