Note that you can query the annotations during runtime:

In [1]: a: int

In [2]: b = 5

In [3]: c: int = 8

In [4]: __annotations__

Out[4]: {'a': int, 'c': int}

In [5]: c = 'foo'

In [6]: __annotations__

Out[6]: {'a': int, 'c': int}

Tinkering with __annotations__ is also needed for hy (python lisp(-like?) language, http://hylang.org/)

Did anyone try this with things that interface with Fortran or C?