anchor.diff:  (define-test test-clos-getters-and-setters
       (let ((ship-1 (make-instance 'spaceship)))
         (set-color :orange ship-1)
  -      (assert-equal ____ (get-color ship-1))
  +      (assert-equal :orange (get-color ship-1))
         (set-speed 1000 ship-1)
  -      (assert-equal ____ (get-speed ship-1))))
  +      (assert-equal 1000 (get-speed ship-1))))
   
   ;; CLOS also provides functionality to create accessors
   ;; to object data.
  
positive.code:       (setf (slot-value car-1 'speed) 220)
        (setf (slot-value car-2 'color) :blue)
        (setf (slot-value car-2 'speed) 240)
        (assert-equal ____ (slot-value car-1 'color))
        (assert-equal ____ (slot-value car-2 'speed))))
  
  ;; CLOS provides functionality for creating getters / setters
  ;; for defined objects
  
negative.code:           (my-circle (make-instance 'circle))
            (my-color (make-instance 'color)))
        (get-kind my-shape)
        (assert-equal :shape *last-kind-accessor*)
        (get-kind my-circle)
        (assert-equal :circle *last-kind-accessor*)
        (get-kind my-color)
        (assert-equal :color *last-kind-accessor*)
        (get-kind my-colored-circle)
        (assert-equal :color *last-kind-accessor*)
        (get-kind my-circled-color)
        (assert-equal :circle *last-kind-accessor*)))
  
  
  ;; Todo: consider adding :before and :after method control instructions.
  