(setq xs '(1 2 3 4 5))
(setq ys '((1 2) (3 4) (5 6)))

(assert (= (length xs) 5))
(assert (= '(5 4 3 2 1) (reverse xs)))
(assert (= 15 (apply + xs) (fold + 0 xs)))
(assert (= 120 (apply * xs) (fold * 1 xs)))

(assert (= (length ys) 3))
(assert (= '((5 6) (3 4) (1 2)) (reverse ys)))
(assert (= '((2 1) (4 3) (6 5)) (map reverse ys)))
(assert (= '(2 2 2) (map length ys)))
(assert (= '(1 2 3 4 5 6) (flatmap identity ys)))
