On 1/8/2016 6:04 PM, Guido van Rossum wrote:

At Dropbox we're trying to be good citizens and we're working towards
introducing gradual typing (PEP 484) into our Python code bases (several
million lines of code). However, that code base is mostly still Python
2.7 and we believe that we should introduce gradual typing first and
start working on conversion to Python 3 second (since having static
types in the code can help a big refactoring like that).

Big +1

I maintain some packages that are single-source 2/3 compatible packages, thus we haven't been able to add type annotations yet (which I was initially skeptical about, but now love) without dropping py2 support. So even for packages that have already been ported to py3, this proposal would be great.

-Robert