(if (eq value +slot-unbound+)
(slot-unbound class instance slot-name)
value)))
#'(lambda (class instance slotd)
(declare (ignore slotd))
(unless (std-instance-p instance) (error "not std"))
(if (eq value +slot-unbound+)
(slot-unbound class instance slot-name)
value)))
#'(lambda (class instance slotd)
(declare (ignore slotd))
(unless (std-instance-p instance) (error "not std"))