code: func (r *ChtRequest) CanSend(peer *peer) bool {
  	peer.lock.RLock()
  	defer peer.lock.RUnlock()
  
  	return peer.headInfo.Number >= r.Config.ChtConfirms && r.ChtNum <= (peer.headInfo.Number-r.Config.ChtConfirms)/r.Config.ChtSize
  }
docs: // CanSend tells if a certain peer is suitable for serving the given request