Vector with a single Z bit (lsb), upper bits all 0.
Definition: *4vec-1z*
(defconst *4vec-1z* (make-honsed-4vec :upper 0 :lower 1))
Macro: 4vec-1z
(defmacro 4vec-1z nil (cons 'quote (cons *4vec-1z* 'nil)))
