LUA: get uservariable index from table?

[blitzkneisser]

is there any possibility to get the index of a user variable from some table? 'uservariables' aparrently contains only name and value and I want to avoid something tedious lieka JSON call, filtering and so on.

There's 'otherdevices_idx' - I'd really like to see something like 'uservariables_idx'
Or is there any other quick way of getting the index?