;; Rectangle=?: Rectangle Rectangle-> boolean
;; Given two Rectangles, produces whether they are
;;    the same.
 (define (Rectangle=? a-Rectangle b-Rectangle)
   (and (posn=? (Rectangle-tl-corner a-Rectangle)
             (Rectangle-tl-corner b-Rectangle))
   (= (Rectangle-width a-Rectangle)
      (Rectangle-width b-Rectangle))
   (= (Rectangle-height a-Rectangle)
      (Rectangle-height b-Rectangle))
   (string=? (Rectangle-clr a-Rectangle)
             (Rectangle-clr b-Rectangle))))

 (check-expect (Rectangle=? R1 R2) false)
 (check-expect (Rectangle=? R2 R3) true)