code: func (h *Handler) registerTxid(msg *pb.ChaincodeMessage) bool {
  	// Check if this is the unique state request from this chaincode txid
  	if h.ActiveTransactions.Add(msg.ChannelId, msg.Txid) {
  		return true
  	}
  
  	// Log the issue and drop the request
  	chaincodeName := "unknown"
  	if h.chaincodeID != nil {
  		chaincodeName = h.chaincodeID.Name
  	}
  	chaincodeLogger.Errorf("[%s] Another request pending for this CC: %s, Txid: %s, ChannelID: %s. Cannot process.", shorttxid(msg.Txid), chaincodeName, msg.Txid, msg.ChannelId)
  	return false
  }
docs: // register Txid to prevent overlapping handle messages from chaincode