prop_emptyIsIntersectionZero :: SetOf e s => s -> Bool
prop_emptyIsIntersectionZero s = (s `intersection` empty) `sameAs` empty
prop_emptyIsIntersectionZero :: SetOf e s => s -> Bool
prop_emptyIsIntersectionZero s = (s `intersection` empty) `sameAs` empty
prop_emptyIsIntersectionZero s = (s `intersection` empty) `sameAs` empty