Recognizer for sign-option structures.
(sign-optionp x) → *
Function:
(defun sign-optionp (x) (declare (xargs :guard t)) (let ((__function__ 'sign-optionp)) (declare (ignorable __function__)) (cond ((not x) (b* nil t)) (t (b* ((fty::val x)) (signp fty::val))))))