-void prout(char *, ...);
-void proutn(char *, ...);
+void prout(const char *, ...) __attribute__((format(printf, 1, 2)));
+void proutn(const char *, ...) __attribute__((format(printf, 1, 2)));
+void prouts(const char *, ...) __attribute__((format(printf, 1, 2)));
+void prstat(const char *txt, const char *fmt, ...)
+ __attribute__((format(printf, 2, 3)));