anchor.diff:     (children-by-id
       :initform (make-hash-table)
       :reader children-by-id-of
  -    :type hash-table)
  -   (out-in-map
  -    :initform (make-hash-table)
  -    :reader out-in-map-of
       :type hash-table)))
   
   
  
positive.code: 
  
  (defclass in-port (port)
    ((owner
      :initarg :owner
      :initform (error ":owner missing")
      :accessor owner-of
      :type simulator)))
  
  
  (defclass out-port (port)
  
negative.code: 	  (values nil nil))
  	(cancel ()
  	  (values nil nil)))
        (if (slot-boundp out 'peer-port)
  	  (values (the in-port (peer-port-of out))
  		  (lock-port sim out obj))
  	  (restart-case (error 'port-not-connected)
  	    (cancel ()
  	      (values nil nil))))))
  
  
  (defmethod access-port ((sim simulator) (in in-port) (obj object))
  