Made exception objects extern.
Added convenience functions.
diff --git a/Include/errors.h b/Include/errors.h
index 35faaa9..c8fc63b 100755
--- a/Include/errors.h
+++ b/Include/errors.h
@@ -8,10 +8,17 @@
void err_clear PROTO((void));
/* Predefined exceptions (in run.c) */
-object *RuntimeError; /* Raised by error() */
-object *EOFError; /* Raised by eof_error() */
-object *TypeError; /* Rased by type_error() */
-object *MemoryError; /* Raised by mem_error() */
-object *NameError; /* Raised by name_error() */
-object *SystemError; /* Raised by sys_error() */
-object *KeyboardInterrupt; /* Raised by intr_error() */
+
+extern object *RuntimeError;
+extern object *EOFError;
+extern object *TypeError;
+extern object *MemoryError;
+extern object *NameError;
+extern object *SystemError;
+extern object *KeyboardInterrupt;
+
+/* Convenience functions */
+
+extern int err_badarg PROTO((void));
+extern object *err_nomem PROTO((void));
+extern object *err_errno PROTO((object *));