code: func (q *graceTerminateRSList) exist(uniqueRS string) (*listItem, bool) {
  	q.lock.Lock()
  	defer q.lock.Unlock()
  
  	if rs, ok := q.list[uniqueRS]; ok {
  		return rs, true
  	}
  	return nil, false
  }
docs: // exist check whether the specified unique RS is in the rsList