#!/usr/bin/perl -w

use strict;
use vars qw($sub);

#exit main(); # Useless use of closure below if called like this
	      # BEGIN block would be needed in this case.

{
	my $time = time();
	$sub = sub {time - $time};
}

exit main(); # No problem, no BEGIN needed.
sub main {
	print &$sub;
	sleep 2;
	print &$sub;
	return 0;
}