Decorators for function annotations

[Dag Odenhall]

I propose the addition of decorators that mimic function annotations in 3.x. For example:

@overload_with_some_decorator_for_generic_functions
@annotate(string_types, integer_types)
def func(arg1, arg2): pass

>>> func.__annotations__
{'arg1': basestring, 'arg2': (int, long)}

@annotate(some_kwarg='hola!')
@returns('greetings from the planet earth')
def func(a, b, c, some_kwarg): pass

>>> func.__annotations__
{'some_kwarg': 'hola!', 'return': 'greetings from the planet earth'}

The Python 3 versions would be:

@overload_with_some_decorator_for_generic_functions
def func(arg1: str, arg2: int): pass

def func(a, b, c, some_kwarg: 'hola!') -> 'greetings from the planet earth': pass

[Benjamin Peterson (benjaminp)]

six is about provide wrappers around things that changed from 2->3, not backporting 3.x features. It seems like this would be easy to include in any project needing it.