tag_assign during VM provisioning

Hello,

I am trying to find a way how to assign a tag to a VM during provisioning.
I copied ManageIQ/Cloud/Provisioning/StateMachines/Provision/default instance to my domain and added new post-provisioning method "AssignTag" to the schema.

I have been trying to create a method that should assign a tag to a VM.

Something like that.

vm = $evm.root['vm']
vm.tag_assign("data_center/london")

but it finishes with error because I don't know a way how to fulfil vm variable.

Could somebody provide a code example.

Many thanks
Karel