code: func (handler *Handler) callPeerWithChaincodeMsg(msg *pb.ChaincodeMessage, channelID, txid string) (pb.ChaincodeMessage, error) {
  	// Create the channel on which to communicate the response from the peer
  	var respChan chan pb.ChaincodeMessage
  	var err error
  	if respChan, err = handler.createChannel(channelID, txid); err != nil {
  		return pb.ChaincodeMessage{}, err
  	}
  
  	defer handler.deleteChannel(channelID, txid)
  
  	return handler.sendReceive(msg, respChan)
  }
docs: // callPeerWithChaincodeMsg sends a chaincode message (for e.g., GetState along with the key) to the peer for a given txid
  // and receives the response.