anchor.diff:      :initarg :fn
       :initform (error ":action missing")
       :accessor fn-of
  -    :type function)))
  +    :type function)
  +   (args
  +    :initarg :args
  +    ;; unbound if unused
  +    :accessor args-of
  +    :type list)))
  +
   
   
   (defclass object (with-id)
  
positive.code:   of obj."))
  
  
  (defgeneric schedule (actor function &key at relative-p)
    (:documentation "TODO"))
  
  
  
negative.code: 	       #'< :key #'time-of)))
  
  
  (defmethod schedule (delay (fn function) (act actor)
  		     &rest args)
    (if (< delay 0)
        (error 'error-invalid)
        (let ((ev (apply 'make-instance
  		       'event
  		       ;; building arguments for make-instance:
  		       ;; if args is nil, leave slot unbound
  		       (append (list :id (fresh-id)
  				     :time (+ delay
  					      (gettime))
  				     :fn fn)
  			       (if (null args)
  				   nil
  				   (list :args args))))))
  	(setf (events-of act)
  	      (sort (cons ev
  			  (events-of act))
  		    #'< :key #'time-of))
  	(values act ev))))
  
  
  (defmethod evolve ((obj object))
  