1try:
2    frozenset
3except NameError:
4    print("SKIP")
5    raise SystemExit
6
7l = [1, 2, 3, 4]
8s = frozenset(l)
9outs = [s.difference(),
10        s.difference(frozenset({1})),
11        s.difference(frozenset({1}), [1, 2]),
12        s.difference(frozenset({1}), {1, 2}, {2, 3})]
13for out in outs:
14    print(type(out), sorted(out))
15
16s = frozenset(l)
17try:
18    print(s.difference_update({1}))
19except AttributeError:
20    print("AttributeError")
21