:destroyed-constant-args (nth-constant-nonempty-sequence-args 1))
(defknown butlast (list &optional unsigned-byte) list (flushable))
(defknown nbutlast (list &optional unsigned-byte) list ()
:destroyed-constant-args (nth-constant-nonempty-sequence-args 1))
(defknown butlast (list &optional unsigned-byte) list (flushable))
(defknown nbutlast (list &optional unsigned-byte) list ()