In April Stripe announced an Open-Source Retreat. A little over a month later they had chosen three grantees.
Though unannounced on the company blog, Andrey Petrov wrote about his experience working on Urllib3 at Stripe for two weeks over on Medium:
Last week completes my two week grant from Stripe to work on urllib3 full time, and I’d like to declare that these weeks were a huge success.
I recommend you read his entire post. What a great thing Stripe did. I hope we see more of it and I hope, in some small way, our company can take part in the future.