package bar;
our $DEFAULT_QUZ = "World";
sub hello {
	my $what = shift || $DEFAULT_QUZ;
	print "Hello, $what!\n";
}

package main;
bar::hello();          # Hello, World!
bar::hello("Alice");   # Hello, Alice!
$bar::DEFAULT_QUZ = "Bob";
bar::hello();          # Hello, Bob!