Yes, I can switch use the ABC instead, and I agree that it doesn't make sense to have the inspect method if it's going to be equivalent to the ABC.

I'm happy with the outcome here but AFAIK the original issue still stands: the Awaitable ABC is unusual in that `isinstance(x, Awaitable)` may produce different results than `issubclass(x.__class__, Awaitable)`. I'd like to see more explicit documentation of the facts that A) functools.singledispatch is not always equivalent to isinstance() and B) Awaitable is one case (the only one in the stdlib?) where this distinction occurs.