Been a while since I've used nim, and never had to do this, but I essentially
want to define a type for a function that takes in a game state, and some object
that the function uses to store state, and returns an updated version of both:
`  SelectionStrategy = func(game: GameState, data: auto): (GameState, auto)`
Where I essentially want to be able to implement and swap out different
algorithms without having to change what data I pass into it, or forcing them to
work on the same data. In some languages you'd use abstract classes for this,
and others I think Monads? But unsure what the right approach for nim would be.

And realized while writing this that it's not actually what I need, but curious
what the answer to this is so wanted to ask it anyways.