code: func (b *Broadcaster) handleBroadcastReq(req *broadcastReq) error {
  	err := b.cfg.Broadcast(req.tx)
  	if err != nil && !IsBroadcastError(err, Mempool) {
  		log.Errorf("Broadcast attempt failed: %v", err)
  		return err
  	}
  
  	b.transactions[req.tx.TxHash()] = req.tx
  
  	return nil
  }
docs: // handleBroadcastReq handles a new external request to reliably broadcast a
  // transaction to the network.