anchor.diff:  
   (defmethod n-destroy ((obj object))
     nil)
  -
  -
  -(defmethod subscribable-states ((obj object))
  -  (list))
   
   
   (defmethod subscribed? ((sub object) (obj object) state)
  
positive.code:   (:nicknames :de-sim.core)
    (:use :common-lisp)
    (:export :imminent-event-time
  	   :subscribable-states :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
  	   :gettime :run-step))
  
  
  
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)))))
  
  