Optional arguments don't have default value
Currently some functions take parameters whose type is `Optional[...]`. For example, the `btnp` function has `hold` and `repeat` parameters with type `Optional[int]`.

But since they don't have any default value, the type hint actually suggests that the argument must be provided. E.g. PyCharm gives a warning saying the argument is missing:

<img width="529" alt="image" src="https://user-images.githubusercontent.com/183207/146649294-0ba01acf-a04d-4bf2-8352-c68a8af94989.png">

To make the warning go away, I have to explicitly pass `None` for both `hold` and `repeat`.

I think the solution here would be to give the parameters default values, e.g. `Optional[int] = None` in the `.pyi` file.