Recognizer for atj-maybe-type structures.
(atj-maybe-typep x) → *
Function:
(defun atj-maybe-typep (x) (declare (xargs :guard t)) (let ((__function__ 'atj-maybe-typep)) (declare (ignorable __function__)) (cond ((not x) (b* nil t)) (t (b* ((fty::val x)) (atj-typep fty::val))))))