anchor.diff:  (defgeneric reset-movable-armies (game)
     (:method ((game game))
      (loop for territory being the hash-values in (territories game) do
  -         (setf (movable-armies territory) (armies territory)))))
  +         (setf (movable-armies territory) (1- (armies territory))))))
   
   (defgeneric move-armies (game from to amount)
     (:method ((game game) origin-key destination-key amount)
  
positive.code: (defclass* game ()
    ((game-map nil r)
     (players nil r)
     (players-round nil)
     (turn-player nil)))
  
  
negative.code:    (with-slots ((the-turn-player turn-player)
                  (the-players-round players-round)) game
       (pop the-turn-player)
       (let ((is-head-player (eq the-turn-player the-players-round)))
         (when is-head-player
           (pass-head game)
           (pop the-turn-player))
         is-head-player))))
  
  (defmethod territories ((game game))
    (territories (game-map game)))
  