;;;;;31.3.4

;; how-many: [Listof X] acc -> Number
;; Counts the number of items in a list using an accumulator
;; Example: (how-many '()) -> 0
;; Example: (how-many '(1 2 3)) -> 3
(define (how-many x acc)
  (cond [(empty? x) acc]
        [else (how-many (rest x) (+ acc 1))]))
(check-expect (how-many '() 0) 0)
(check-expect (how-many '(1 2 3) 0) 3)

(generate-report)