Thanks for the feedback Nick! If I get a chance I'll see about refactoring my gist into a base class and two sub-classes with the async supporting non-async but not vice-versa.  I think it will be cleaner.  Sorry I didn't spend too much effort on the existing gist as I tried quickly layering on async support to move on to my primary task.  After doing that I noticed that the code could use some refactoring, but only after taking the time deconstructing the impl to understand how the code works.