exit, die -- Kills the current script.
sub::exit kills all the subprocesses of the current program. If an integer argument is given, sub::exit exits with the status. Otherwise, sub::exit shows the given message and exits with status 0. sub::die shows a stack trace and delegates arguments to sub::exit.
// 1-a. Command form with a message.
void sub::exit(string message)
// 1-b. Command form with a status.
void sub::exit(int status = 0)
// 1-c. Command form with a message.
void sub::die(string message)
// 1-d. Command form with a status.
void sub::die(int status = 0)