This lesson mixes the whole Collections unit on one dataset: a gym's membership list, as a list of dictionaries, plus a few smaller lists and sets.
Some exercises want a list, some a dictionary, a set or a tuple. Read each prompt for the shape of the answer as well as the values: the checker tells you when the values are right but the container isn't.
Expect the edge cases from the unit to come back: duplicates, missing keys, slices that stop one short, and copies that turn out to be the same list.