> >  Looking at PEP 484, I came up with two use cases that I felt were not
> > catered for:
> >
> >    1. Specifying that a parameter should be a subclass of another
> >    (example: Type[dict] would match dict or OrderedDict; plain "Type" would
> >    equal "type" from builtins)
> >
> >
> I don't understand. What is "Type"? Can you work this out in a full
> example? This code is already okay:
>
> def foo(a: dict):
>     ...
>
> foo(OrderedDict())

I think Alex means this: https://github.com/ambv/typehinting/issues/107
This could be really useful, for example:

def fancy_instantiate(cls: Type[T]) -> T:
    ...