PendingDeprecationWarning is really useful?

[Senthil (Senthil Kumaran)]

@brettcannon

I’ve contemplated adding something to warnings where you specify what version of Python something is scheduled to be removed in and then it would raise PendingDeprecationWarning in >N version, DeprecationWarning in N, and raise a RuntimeError or something for N+1 so it doesn’t get forgotten.

I really this. This will force us to remove the APIs that are promised for Deprecation.