I've named it _compat because a) It doesn't have to be a public module b) _compat is somewhat best practice.

See for example:
* https://github.com/mitsuhiko/jinja2/blob/master/jinja2/_compat.py
* https://github.com/hylang/hy/blob/master/hy/_compat.py
* https://github.com/mitsuhiko/flask/blob/master/flask/_compat.py