#!/usr/bin/perl

my $code = do {
    my $x = 1;
    my $y = 0;
    my $next;
    $next = sub {
        ($y, $x) = ($x, $x + $y);
        return ($next, $x);
    };
};

my $value;

while($code) {
    ($code, $value) = $code->();
    print "Next value is: $value \n";
    if ($value > 100000000) { last };
}