[$] Classes and types in the Python typing module

Mark Shannon is concerned that the Python core developers may be replayinga mistake: treating two distinct things as being thesame. Treating byte strings and Unicode text-strings interchangeably ispart of what led to Python 3, so he would rather not see that happenagain with types and classes. The Python typingmodule, which is meant to support type hints, currentlyimplements types as classes. That leads to several kinds of problems, asShannon described in his session at the 2017 Python Language Summit.