-- | @memberWithin' n a@ checks to see whether an element is within a
-- 'Closed' set after @n@ improvements.
memberWithin :: (Hashable a, Eq a) => Int -> a -> Closed a -> Bool
memberWithin n a = fst . memberWithin' n a
memberWithin :: (Hashable a, Eq a) => Int -> a -> Closed a -> Bool
memberWithin n a = fst . memberWithin' n a
memberWithin n a = fst . memberWithin' n a