anchor.diff:  (defmethod (setf slot-value-using-class) (new-value (class std-class) instance (slot standard-effective-slot-definition))
     (setf (std-slot-value instance (slot-definition-name slot)) new-value))
   
  +(defgeneric (sys.int::cas slot-value-using-class) (old new class instance slot))
  +(defmethod (sys.int::cas slot-value-using-class) (old new (class std-class) instance (slot standard-effective-slot-definition))
  +  (sys.int::cas (std-slot-value instance (slot-definition-name slot)) old new))
  +
   (defgeneric slot-boundp-using-class (class instance slot))
   (defmethod slot-boundp-using-class ((class std-class) instance (slot standard-effective-slot-definition))
     (std-slot-boundp instance (slot-definition-name slot)))
  
positive.code:                  (t
                    (slot-missing (class-of object) object slot-name 'setf new-value)
                    new-value))))))
  
  (defun std-slot-boundp (instance slot-name)
    (multiple-value-bind (slots location)
  
negative.code:   (if (consp location)
        (setf (cdr location) new-value)
        (setf (svref slots location) new-value)))
  
  (defun (sys.int::cas slot-contents) (old new slots location)
    (if (consp location)
        (sys.int::cas (cdr location) old new)
        (sys.int::cas (svref slots location) old new)))
  
  (defun fast-sv-position (value simple-vector)
    (dotimes (i (array-dimension simple-vector 0))
  