Type annotations

[surgura]

I really like the idea of this library. I could not find any other libraries that provide the same functionality, and I think this is a valuable and somehow unused contribution to the community. However, to provide the same user experience as if using the collections themselves, I think type annotations should be provided. I will try and pick that up, and, if welcome, make a PR some time later.

[surgura]

Before I do anything: your library supports Python 2. While naturally I respect that, I personally do not want to provided this compatibility in my contributions. Simply let me know if you think Python 2 is crucial to your project, then I will make a python 3-only fork instead of a PR.

Surgura