check-in working versions of series.py and ack.py; need more work on the...

... asserts
Although I agree with @jefrailey here on the use of `_` as a stub symbol, do be a bit careful about that.  When working with systems that support translations, it is often the case that the `_` symbol is used to bind to the translation factory.  Several internationalization and localization libraries scan code looking for `_` as a function that will mark UI strings intended to be localized.  

This is not important in this case, but it *is* something to be aware of in your future as a pythonista