Recognizer for standard characters whose guard is t
Logically standard-char-p+ is the same as standard-char-p. However, standard-char-p+ has a guard of t, while standard-char-p is guarded by characterp.
Function: standard-char-p+
(defun standard-char-p+ (x) (declare (xargs :guard t)) (and (characterp x) (standard-char-p x)))
