Implement:
invert(d): swap keys and values. If two keys share a value, raise ValueError naming that value. That's a common silent bug when inverting naively.invert_multi(d): map each value to a sorted list of all keys that had it.invert_lists(d): the input maps keys to lists of values (like {"admin": ["alice", "bob"]}). Return a dict mapping each value to the sorted list of keys whose list contains it.