anchor.diff:    (setf *cells-count* 100)
     (setf *cell-size* (/ *pixel-size* *cells-count*))
     (setf *matrix* (matrix-create *cells-count*))
  +  (setf *old-matrix* (matrix-create *cells-count*))
     (iterate #'(lambda (x y)
  -	       (matrix-set *matrix* x y (= (random 2) 0)))
  +	       (matrix-set *matrix* x y (= (random 10) 0)))
   	   *cells-count*)
     (setf *dead-color* (sdl:color :r 255 :g 0 :b 0))
     (setf *alive-color* (sdl:color :r 0 :g 0 :b 0)))
  
positive.code: (defun game-count-alive (x0 y0)
    (let ((alive-count 0))
      (iterate-near #'(lambda (x y)
  		      (when (matrix-get *matrix* x y)
  			(setf alive-count (add1 alive-count))))
  		  x0
  		  y0)
      alive-count))
  
  ;;; Draw
  ;;; ====
  
negative.code: (defun game-step ()
    (iterate #'(lambda (x y)
  	       (let ((count (game-count-alive x y))
  		     (alive (matrix-get *old-matrix* x y)))
  		 (if alive
  		     (if (or (= count 2) (= count 3))
  			 'survives
  