(reverse '(1 2 3 4 5)) ⇒ (5 4 3 2 1)
Q: What is the reverse of the empty list?
A: The empty list
Q: If you had the reverse of a list's tail, how would you get the reverse of the whole list?
A: Add the head of the list to the end of the reversed tail.
(define reverse
(lambda (lst)
(if (null? lst)
'()
(add-to-end (reverse (cdr lst)) (car lst)))))