anchor.diff:    nil)
   
   
  +(defclass in-port (with-id)
  +  nil)
  +
  +
  +(defclass out-port (with-id)
  +  nil)
  +
  +
   (defclass actor (object)
  -  ((events
  -    :initform (list)
  +  ((in-ports
  +    :initarg :in-ports
  +    :initform (list)
  +    :accessor in-ports-of
  +    :type list)
  +   (out-ports
  +    :initarg :out-ports
  +    :initform (list)
  +    :accessor out-ports-of
  +    :type list)
  +   (events
       :accessor events-of
  +    :initform (list)
       :type list)))
   
   
  
positive.code: 
  
  (deftype time-type ()
    '(or (integer 0)
      nil))
  
  
  
  
negative.code: 
  (defmethod schedule ((act actor) (fn function)
  		     &key (at 0) (relative-p t) (id 0 id-p))
    (declare (time-type at)
  	   (id-type id))
  
    (let ((abs-time (+ at (if relative-p
  			    (gettime)
  			    0))))
  