anchor.diff:  
     name-symbol |
     ( name-symbol [ (:conc-name conc-name ) ]
  -                [ (:predicate predicate-name ) ] )
  +                [ (:predicate predicate-name ) ]
  +                class-option* )
   
   SUPERS - a list of super classes passed directly to DEFCLASS.
   
  
positive.code:                (error "Can't specify the :PREDICATE argument more than once."))
               (setf predicate (if (eql t (first args))
                                   (intern (strcat class-name :-p) *package*)
                                   (first args))))))
      (setf slots
            (mapcar
             (lambda (slot-spec)
  
negative.code:                   (defmethod ,predicate ((,obj t)) nil)))
                nil))
      `(prog1
           (defclass ,class-name ,supers ,slots ,@(nreverse class-options))
         ,@predicate-forms)))
  
  ;; Copyright (c) 2002-2006, Edward Marco Baringer
  