infer async return types

[theoephraim]

Very cool tool. I've tried a bunch of the alternatives and this one seems to work fairly well :)

However, as mentioned in https://github.com/ccontrols/structured-types/issues/8, it would be great if this tool could handle inferred async return types.

I'd rather not go through my codebase and add explicit returns on every async method if possible.

Cheers!