code: func (a *Announce) maybeAnnouncePeer(to Addr, token *string, peerId *krpc.ID) {
  	if token == nil {
  		return
  	}
  	if !a.server.config.NoSecurity && (peerId == nil || !NodeIdSecure(*peerId, to.IP())) {
  		return
  	}
  	a.server.mu.Lock()
  	defer a.server.mu.Unlock()
  	a.server.announcePeer(to, a.infoHash, a.announcePort, *token, a.announcePortImplied, nil)
  }
docs: // Announce to a peer, if appropriate.