https://mail.python.org/pipermail/python-dev/2012-December/123028.html https://mail.python.org/pipermail/python-dev/2012-December/1... and https://www.python.

https://mail.python.org/pipermail/python-dev/2012-December/123028.html https://mail.python.org/pipermail/python-dev/2012-December/1... and https://www.python.org/dev/peps/pep-0468/ https://www.python.org/dev/peps/pep-0468/ The implementation is based off of PyPy's "compact" dictionary implementation.