Another kind of pointer arithmetic

[Ianis Vasilev]

Somebody joked yesterday on Twitter about how pointer levels of 
indirection can be used to represent natural numbers and how we 
can do arithmetic with them (I can't find the post right now).

I decided to try and implement adding and multiplying levels of 
indirection:
https://gist.github.com/v--/5cbd0046be6fc5dbff9a9ad2f1717cde

I think it turned out fairly trivial.