Play audio slide show -- Keyboard shortcut: 'x'  Back to slide -- Keyboard shortcut: 'u'        next -- Keyboard shortcut: 'n'  Annotated program -- Keyboard shortcut: 't'      number-interval.scm - The function number-interval-iter is an iterative, tail recursive variant of number-interval.Lecture 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))