anchor.diff:    (:nicknames :de-sim.core)
     (:use :common-lisp)
     (:export :imminent-event-time
  -	   :subscribable-states :subscribed? :subscribe :unsubscribe
  +	   :subscribed? :subscribe :unsubscribe
   	   :n-event-choosed :n-destroy
   	   :id-of
   	   :event :time-of :fn-of :args-of
  -	   :object :description :description-of :events-of
  -	           :subscriptions-of :notifications :notifications-of
  -		   :notify-subscribed
  +	   :object :subscribable-states :subscribable-states-of
  +	           :description :description-of :events-of
  +		   :subscriptions-of :notifications :notifications-of
  +	   :notify-subscribed
   	   :gettime :run-step))
   
   
  
positive.code: 
  (defmethod n-destroy ((obj object))
    nil)
  
  
  (defmethod subscribable-states ((obj object))
    (list))
  
  
  (defmethod subscribed? ((sub object) (obj object) state)
  
negative.code:     (defmethod initialize-instance :after ((obj object) &key)
        (setf (id-of obj)
  	    (incf id-counter))
        (dolist (ss (subscribable-states-of obj))
  	(setf (gethash ss (subscriptions-of obj))
  	      (list)))))
  
  