MQTT Broker - logging irule

Hi

i am trying to setup an MQTT LTM VS and running into a few issues, i was trying to use some of the sample irules to capture some more logging but can't quite figure out this one that should log the messages

https://techdocs.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-iot-administration-13-0-0/1.html

Common/irule_mqtt_loggging:14: error: [undefined procedure: MQTT::message_id][MQTT::message_id]

/Common/irule_mqtt_loggging:26: error: ["The command does not expect argument."][MQTT::message topics qos $topic]

i had thought that these were standard variables that could just be used...if anyone has managed to get this working any help would be apprecated

thanks

chris