anchor.diff:      (aref fact-vector (1- (length fact-vector)))))
   
   (defun token-push-fact (token fact)
  -  (vector-push-extend fact (slot-value token 'facts)))
  +  (vector-push-extend fact (slot-value token 'facts))
  +  token)
   
   (defun token-pop-fact (token)
     (with-slots ((fact-vector facts)) token
  
positive.code:   ((facts :initform
            (make-array 0 :adjustable t :fill-pointer t)
            :reader token-facts)))
  
  (defmethod initialize-instance :after ((self token) &key fact)
    (unless (null fact)
      (vector-push-extend fact (slot-value self 'facts)))
    self)
  
  (defclass add-token (token) ())
  (defclass remove-token (token) ())
  
negative.code: ;;; File: token.lisp
  ;;; Description:
  
  ;;; $Id: token.lisp,v 1.10 2002/09/11 01:50:24 youngde Exp $
  
  (in-package "LISA")
  
  