code: func (s *holderSyncer) IsClosing() bool {
  	if s.Cluster.abortAntiEntropyQ() {
  		return true
  	}
  	select {
  	case <-s.Closing:
  		return true
  	default:
  		return false
  	}
  }
docs: // IsClosing returns true if the syncer has been asked to close.