(test-constraint nil :type (or sset null)))
(def!method print-object ((cblock cblock) stream)
(print-unreadable-object (cblock stream :type t :identity t)
(test-constraint nil :type (or sset null)))
(def!method print-object ((cblock cblock) stream)
(print-unreadable-object (cblock stream :type t :identity t)