1l = [1, 2, 3, 4]
2s = set(l)
3outs = [s.difference(),
4        s.difference({1}),
5        s.difference({1}, [1, 2]),
6        s.difference({1}, {1, 2}, {2, 3})]
7for out in outs:
8    print(sorted(out))
9
10s = set(l)
11print(s.difference_update())
12print(sorted(s))
13print(s.difference_update({1}))
14print(sorted(s))
15print(s.difference_update({1}, [2]))
16print(sorted(s))
17
18s.difference_update(s)
19print(s)
20