+/* 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);
+
+/* Return next token from "line", or NULL if none is found. Tokens either a)
+ * start at the first non-whitespace character and end before the next
+ * whitespace character after that; or b) if the first non-whitespace character
+ * is a single quote followed by at least one other single quote some time later
+ * on the line, the token starts after that first single quote and ends before
+ * the second, with the next token_from_line() call starting its token search
+ * after that second quote. The only way to return an empty string (instead of
+ * NULL) as a token is to delimit the token by two succeeding single quotes.
+ */
+extern char * token_from_line(char * line);