use Iterator;

my $i = 0;
sub get_a {
    return new Iterator(sub { print "a called\n"; return $i++ });
}

sub get_b {
    my $a = get_a;
    return new Iterator(sub { print "b called\n"; return $a->value });
}

print "Now I will get_b ($i):\n";
$b = get_b;
print "Got b ($i)\n";
print "First value is ($i):\n";
print "b: ", $b->value, " ($i)\n";