def METHOD_NAME():
    for ((f1, f2), (k1, k2)) in COMBINATIONS2:
        s1 = f1()
        s2 = f2()
        s1.add(k1)
        s2.add(k2)
        res = s1 & s2
        assert 2 not in res
        assert 'bar' not in res
        if k1 == k2:
            assert k1 in res
            assert len(res) == 1
        else:
            assert k1 not in res
            assert k2 not in res
            assert len(res) == 0