anchor.diff:    (let ((player-1 (make-basketball-player
                      :name "larry" :team :celtics :number 33)))
       (assert-equal "larry" (basketball-player-name player-1))
  -    (assert-equal ___ (basketball-player-team player-1))
  -    (assert-equal ___ (basketball-player-number player-1))
  +    (assert-equal :celtics (basketball-player-team player-1))
  +    (assert-equal 33 (basketball-player-number player-1))
       (assert-equal 'basketball-player (type-of player-1))
       (setf (basketball-player-team player-1) :RETIRED)
  -    (assert-equal ___ (basketball-player-team player-1))))
  +    (assert-equal :RETIRED (basketball-player-team player-1))))
   
   
   ;; Struct fields can have default values
  
positive.code: 
  (define-test test-struct-defaults
      (let ((player-2 (make-baseball-player)))
        (assert-equal ___ (baseball-player-position player-2))
        (assert-equal ___ (baseball-player-team player-2))
        (assert-equal ___ (baseball-player-name player-2))))
  
  
  ;; The accessor names can get pretty long.  It's possible to specify
  
negative.code: (define-test test-abbreviated-struct-access
      (let ((player-3 (make-american-football-player
                       :name "Drew Brees" :position :QB :team "Saints")))
        (assert-equal :QB (nfl-guy-position player-3))))
  
  
  ;; Structs can be defined as EXTENSIONS to previous structures.
  