Indeed, here is the mail from Raymond Hettinger explaining the new design on the python-dev list: https://mail.python.org/pipermail/python-dev/2012-December/1... Quite amazing that it is faster, more memory efficient and convenient for the end user.

Raymond came up with the idea, PyPy implemented it, and then INADA Naoki implemented it for CPython.

If I remember correctly his talk. He went to CPython first and it was rejected, but PyPy welcomed it.

It was proposed by Raymond Hettinger, but was actually first implemented by PHP and Pypy.