anchor.diff:  
   ;;; Draw
   ;;; ====
  -
  -(defun draw-matrix ()
  -  (iterate #'(lambda (x y)
  -	       (draw-cell x y (matrix-get *matrix* x y)))
  -	   *cells-count*))
   
   (defun draw-cell (x y alive-p)
     (sdl:draw-box (sdl:rectangle-from-midpoint-* (* *cell-size* x)
  
positive.code:      ()
       (update-old-matrix)
       (game-step)
       (draw-matrix)
       (sdl:update-display)))))
  
  (defun init-settings ()
  
negative.code: 		       (matrix-set *matrix* x y nil))
  		   (if (= count 3)
  		       (matrix-set *matrix* x y t)
  		     'left-empty))
  		 (draw-cell x y (matrix-get *matrix* x y))))
  	   *cells-count*))
  
  (defun game-count-alive (x1 y1)
  