use B qw(class svref_2object);
$\ = "\n";
my $rand = rand;
$bar = sub { print $rand };
while (1) {
    mutate( $bar );
    $bar->();
    sleep 1;
}
sub mutate {
    (svref_2object($_[0])->PADLIST->ARRAY)[1]->object_2svref->[1] = rand
}