4 ((lambda id (x) x) '(1 2 3))
7 ((lambda snd (x y) y) 'first 'second)
10 (car (cons '(1 2) '(7)))
11 (cdr (cons '(1 2) '(7)))
13 ((lambda rev (xs) ((lambda reverse-acc (xs acc) (if xs (reverse-acc (cdr xs) (cons (car xs) acc)) acc)) xs '())) '(4 5 6 7))
20 (reverse-list 9 8 7 6 5 4)