`use v6;` is not mandatory in Rakudo. Off the top of my head, I don't think it's mandatory in theory in Perl 6, either. However, it is widely used to mark Per

`use v6;` is not mandatory in Rakudo. Off the top of my head, I don't think it's mandatory in theory in Perl 6, either. However, it is widely used to mark Perl 6 code, because it gives you a nice clean error message if you accidentally try running it in Perl 5.