(a)
(define-cbr-as-cbv do-f (arg ...)
   () body)

(b)
(define-cbr (f a b)
   (swap a b))

(c)
(begin
   (define-cbr-as-cbv do-f (a b)
      () (swap a b))
   (define do-f . . .))

(d)
(begin
   (define-cbr-as-cbv do-f ()
      ((a get1 set1) (b get2 set2)) (swap a b))
   (define do-f . . .))

Example 10: Replacement for ???.