A simple implementation of the pretty recent W3C WebDriver spec.
I have coded this library during a livestream, if you want to learn more about it's internals and how it can be used take a look: https://www.youtube.com/watch?v=583BwZ7uSro&index=1&list=PLm-fq5xBdPkrMuVkPWuho7XzszB6kJ2My
I have prepared an example repo showing how to test a sample Jester app using Travis with this library, available here: https://github.com/dom96/geckodriver-travis.
For a larger example you can have a look at the Nimforum: https://github.com/nim-lang/nimforum/tree/7d8417ff97/tests