(defknown list-length (list) (or index null) (foldable unsafely-flushable))
(defknown nth (index list) t (foldable flushable))
(defknown nthcdr (index list) t (foldable unsafely-flushable))
(defknown list-length (list) (or index null) (foldable unsafely-flushable))
(defknown nth (index list) t (foldable flushable))
(defknown nthcdr (index list) t (foldable unsafely-flushable))