+(defgeneric fmt-rui (rui))
+(when *has-fixnum-class*
+ (defmethod fmt-rui ((rui fixnum))
+ (prefixed-fixnum-string rui #\A 8)))
+
+(defmethod fmt-rui ((rui integer))
+ (prefixed-integer-string rui #\A 8))
+
+(defmethod fmt-rui ((rui string))
+ (if (eql (aref rui 0) #\R)
+ rui
+ (fmt-rui (parse-integer rui))))
+