(set-slot 'can-precede-list (classes (cdr cpl)))
(set-slot 'incompatible-superclass-list nil)
(set-slot 'direct-superclasses (classes direct-supers))
(set-slot 'can-precede-list (classes (cdr cpl)))
(set-slot 'incompatible-superclass-list nil)
(set-slot 'direct-superclasses (classes direct-supers))