anchor.diff:  ;return entrance
   (defun populate-map (new_map)
     (loop for i below (length new_map)
  -    do (setf (aref new_map i) (make-item :kind 'potion)))
  +    do (setf (aref new_map i) (funcall (nth (random (length *item-builders*)) *item-builders*))))
   )
       
   (defun reveal-map (map_history)
  
positive.code: (setf (aref *inventory* 0) (make-sword))
  (setf (aref *inventory* 1) (make-shield))
  
  (defmethod view-item (item)
    "Empty"
  )
  
negative.code: 
  (defun pickup-item ()
    (let ((player-x (car (player-position *player*)))
          (player-y (cdr (player-position *player*)))
         )
    
    (loop for i below (length *inventory*)
  