(define (c- z y)
  (let ((x (make-connector))
       (adder x y z)
       x)))

(define (c* x y)
  (let ((z (make-connector)))
       (multiplier x y z)
       z))

(define (c/ z y)
  (let ((x (make-connector)))
       (multiplier x y z)
       x))

(define (cv x)
  (let ((v (make-connector)))
       (constant v x)
       x))