https://github.com/pantsbuild/pants/pull/8639 <= allowing `async def`/`await` in `@rule`s actually results in a smaller PR and doesn't require changing the annotated return type to satisfy mypy completely, was super super annoying to figure out the magical interaction between `yield`ing in an

__await__()

implementation, but it's super exhilarating to be able to just

x: X = await Get(X, Y(...))