code: func (q *Query) LogReplay() *Query {
  	q.m.Lock()
  	q.op.flags |= flagLogReplay
  	q.m.Unlock()
  	return q
  }
docs: // LogReplay enables an option that optimizes queries that are typically
  // made on the MongoDB oplog for replaying it. This is an internal
  // implementation aspect and most likely uninteresting for other uses.
  // It has seen at least one use case, though, so it's exposed via the API.