Ensure uniqueness, i guess? Though you'd lose that when you make the list of sets. I could maybe see something like this as an intermediary result of parsing s

Ensure uniqueness, i guess? Though you'd lose that when you make the list of sets. I could maybe see something like this as an intermediary result of parsing some horrible, nested obscure message format (except the dict, that baffles me unless the key-value types are reversed?)