Stop show with sound  Next slide in show -- Keyboard shortcut: 'n'  2 minutes, 20 secondsLecture 3 - slide 21 : 42
Program 1
(define (number-interval-iter f t)
  (reverse (number-interval-iter-help f t '())))


(define (number-interval-iter-help f t res)
  (if (<= f t)
      (number-interval-iter-help (+ f 1) t (cons f res))
      res))