Validate multiple RadioButtonLists at once

I have a scenario where I am creating one or many RadioButtonLists on the fly.

Each RadioButtonList displays a distinct group of values that the user can select. The catch is however, they can only choose one item from ALL of the groups together (even though they must still be grouped separately in separate RadioButtonLists).

How can I validate this with javasript, bearing in mind that the lists are dynamically generated and thus I don't know how many I will end up with?
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