[$] Python virtual environments

In a short session at the 2018 Python Language Summit, Steve Dower brought
up the shortcomings of Python virtual environments,
which are meant to create isolated installations of the language and its
modules. He said his presentation was "co-written with Twitter" and,
indeed, most of his slides were of tweets. At the end, he also slipped in an
announcement of his plans for hosting a core development sprint in September.