+extern void set_err_line_options(char * intro, char * line, uint32_t count,
+ uint8_t exit);
+
+/* If "test", output "msg", faulty line, its number and exit if so defined by
+ * set_err_line_options(), else return 1 on "test" and 0 if "test" is 0.
+ */
+extern uint8_t err_line(uint8_t test, char * msg);