Mypy 0.900 Released

Not a Python user myself, but Mypy certainly looks interesting. We're currently using Sorbet with Ruby, and it's a great tool, but Mypy seems to be evolving much more rapidly. See, for example, TypeGuard in the submitted link - something TypeScript also has, but we'll probably be waiting a long time for in Ruby land, if we ever see it.

Curious to hear about people's experiences with Mypy!