code: def set_id(self, id='$'):
          
          accum = {}
          for key in self.keys:
              accum[key] = self.database.xgroup_setid(key, self.name, id)
          return accum
docs: Set the last-read message id for each stream in the consumer group. By
          default, this will be the special "$" identifier, meaning all messages
          are marked as having been read.
  
          :param id: id of last-read message (or "$").