They've made backward incompatible changes within python 3's history, but none of the things you've listed are among them. Anything with ':='s, f'strings' etc.

They've made backward incompatible changes within python 3's history, but none of the things you've listed are among them. Anything with ':='s, f'strings' etc. is invalid in python 3.0, so existing [working] code isn't affected. With 2 vs 3 there were a large number of breaking changes, so effort spent adding new features to the 2.x lineage made sense. But if you're not able to get someone to update from 3.6 to 3.7 for dataclasses, is a 3.6.7 that supports them [but doesn't reserve 'async'] likely to be any different? > Are you using features that are only available in the version of Python all your colleagues / users have access to? Are you using the latest version of Python and hoping your colleagues and users can upgrade to that version of Python? If you have access our software, you have access to http://python.org http://python.org -- that's never the issue. For colleagues... everyone has 3.6.4-3.6.6 on their work computers unless they've actively prevented it. We don't have anything using python for external users. If we did, I wouldn't want to assume that they already have python installed at all. I'd be inclined to look into PyInstaller for distributing that, and then we could depend on whatever version we wanted.