code: func (k *Kademlia) CloseAddrCountC() {
  	k.lock.Lock()
  	defer k.lock.Unlock()
  
  	if k.addrCountC != nil {
  		close(k.addrCountC)
  		k.addrCountC = nil
  	}
  }
docs: // CloseAddrCountC closes the channel returned by
  // AddrCountC and stops sending address count change.