code: func (pool *serverPool) registered(entry *poolEntry) {
  	log.Debug("Registered new entry", "enode", entry.node.ID())
  	req := &registerReq{entry: entry, done: make(chan struct{})}
  	select {
  	case pool.registerCh <- req:
  	case <-pool.quit:
  		return
  	}
  	<-req.done
  }
docs: // registered should be called after a successful handshake