isSubsetOf :: Ord a => CustomSet a -> CustomSet a -> Bool
isSubsetOf a b = size a <= size b && F.all (`member` b) a
isSubsetOf :: Ord a => CustomSet a -> CustomSet a -> Bool
isSubsetOf a b = size a <= size b && F.all (`member` b) a
isSubsetOf a b = size a <= size b && F.all (`member` b) a