lsd6 set 4

from functools import reduce


def partition(f, s):
    good = set()
    bad = set()

    def process(prev, curr):
        if f(curr):
            good.add(curr)
        else:
            bad.add(curr)

    reduce(process, s, -1)
    return good, bad


print(partition(lambda x: x % 2 == 0, {1, 2, 3, 4}))