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:                      (cdr (ensure-list name-and-options))
                       supers slots))
  
  (defun generate-defclass (class-name class-options supers slots)
    (let ((conc-name nil)
          (predicate nil)
          (predicate-forms nil))
      (loop
         for (option-name . args) in class-options
         do (ecase option-name
              (:conc-name
               (when conc-name
                 (error "Can't specify the :CONC-NAME argument more than once."))
  
negative.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))))
              (t
               (push (cons option-name args) class-options))))
      (setf slots
            (mapcar
             (lambda (slot-spec)
  