code: func (k *Kademlia) sendNeighbourhoodDepthChange() {
  	// nDepthC is initialized when NeighbourhoodDepthC is called and returned by it.
  	// It provides signaling of neighbourhood depth change.
  	// This part of the code is sending new neighbourhood depth to nDepthC if that condition is met.
  	if k.nDepthC != nil {
  		nDepth := depthForPot(k.conns, k.NeighbourhoodSize, k.base)
  		if nDepth != k.nDepth {
  			k.nDepth = nDepth
  			k.nDepthC <- nDepth
  		}
  	}
  }
docs: // sendNeighbourhoodDepthChange sends new neighbourhood depth to k.nDepth channel
  // if it is initialized.