Complete Program from Figure 10

(define Basic-Shapes
  (unit (import) 
        (export Shape Rectangle Circle Translated)
        
     (define Shape (interface () draw))
        
     (define Rectangle
       (class* object% (Shape) (width height)
         (public
           [draw (lambda (dc x y)
                   (send dc draw-rectangle x y width height))])
         (sequence (super-init))))
     
     (define Circle
       (class* object% (Shape) (radius)
         (public
           [draw (lambda (dc x y)
                   (send dc draw-ellipse
                         (- x radius)
                         (- y radius)
                         (* 2 radius)
                         (* 2 radius)))])
         (sequence (super-init))))
     
     (define Translated
       (class* object% (Shape) (orig-shape dx dy)
         (public
           [draw (lambda (dc x y)
                   (send orig-shape draw 
                         dc (+ x dx) (+ y dy)))])
         (sequence (super-init))))))


(define Union-Shape
  (unit (import Shape)
        (export Union)

    (define Union
      (class* object% (Shape) (left right)
	(public
	  [draw (lambda (dc x y)
		  (send left draw dc x y)
		  (send right draw dc x y))])
        (sequence (super-init))))))

(define Basic+Union-Shapes 
  (compound-unit 
   (import)
   (link [S (Basic-Shapes)]
	 [US (Union-Shape (S Shape))])
   (export (S Shape)
           (S Rectangle)
           (S Circle)
           (S Translated)
           (US Union))))

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