Layout / KDL : Substitute arg of command with the value of another node

[tomschelsen]

This is maybe more a KDL problem than a Zellij one but as I couldn't find a solution I'm taking a chance here :

Is there a way to pass as an arg of a command a value declared elsewhere in the layout KDL file ? What I would like to do :

versions {
    module1 "v4"
    module2 "v1"
}

layout {
    pane name="Mod1" { 
        command "./run_mod1.sh"
        args "${{ versions.module1 }}"
    }
    pane name="Mod2" { 
        command "./run_mod2.sh"
        args "${{ versions.module2 }}"
    }
}

I found the "${{ node.child }}" syntax in one of the KDL repo examples but here it doesn't work, bash tells me "wrong substitution".

Many thanks