docs: def Copy(self):
      """Return a copy of the queue manager.
  
      Returns:
      Copy of the QueueManager object.
      NOTE: pending writes/deletions are not copied. On the other hand, if the
      original object has a frozen timestamp, a copy will have it as well.
      """
      result = QueueManager(store=self.data_store, token=self.token)
      result.prev_frozen_timestamps = self.prev_frozen_timestamps
      result.frozen_timestamp = self.frozen_timestamp
      return result