anchor.diff:                                                          (0 0 0 0 0 0 0 0 0 0)))
     "The grassy knoll where player starts")
   
  -(defparameter *level-1* (make-array '(10 10)
  +(defparameter *layer-1* (make-array '(10 10)
                                       :initial-contents '((2 2 2 2 2 2 2 2 2 2)
                                                           (2 2 2 2 2 2 2 2 2 2)
                                                           (2 2 2 2 2 2 2 2 2 2)
  
positive.code:                                                         (2 2 2 2 2 2 2 2 2 2)))
    "The grassy floor beneath the player where she starts")
  
  (defparameter *world* (list *level-0* *level-1*)
    "The *world* is a list made of 10x10 levels")
  
  (defun add-level ()
    (push (make-array '(10 10)) *levels*))
  
  (defun reset-world ()
    (setf *level-0* (make-array '(10 10) :initial-element 1))
    (setf *world* (list *level-0* *level-1*)))
  
  (defun value-at (x y)
    (aref (level-under-player) y x))
  
  (defun level-value-at (level x y)
    (aref level y x))
  
  (defun level-under-player ()
    (nth (+ (altitude *player*) 1) *world*))
  
  (defun level-at-player ()
    (nth (altitude *player*) *world*))
  
  (defun level-above-player ()
    (nth (- (altitude *player*) 1) *world*))
  
  
  
negative.code: ;;; [ ]  Add function to write out the world so it can persist
  
  
  (defparameter *layer-0* (make-array '(10 10)
                                      :initial-contents '((0 0 0 0 0 0 0 0 0 0)
                                                          (0 0 0 0 0 0 0 0 0 0)
                                                          (0 0 0 0 0 0 0 0 0 0)
  