I've glanced at the code now. You are absolutely correct.

Wow.

There's some good reasons to think this approach won't work at all. If I understand it correctly I think it is attempting to predict part of speech using previously observed values.

That's an interesting idea, and might be somewhat valuable as a feature to use in a text generator, but on its own won't be enough to ever generate sentences that make sense (because some specific sequences just don't make sense).