Add type hints

[leftshift]

I've recently jumped on the train of sprinkling type hints into python projects as this can help find problems and understand code.

As we're mostly returning plain responses from an api we don't have control over, type hints for those responses would probably be of limited use and potentially hard to maintain.

Still, adding hints for function arguments may be a good idea.

[pylipp]

I'd find it particularly interesting to create a CLI based on type hinting in the library, e.g. by using typer. This could be installed as extra option.