From the README:
Pew is written in pure python and leverages inve: the idea for a better activate script.
That inve link, https://gist.github.com/datagrok/2199506, used to be the article "Virtualenv’s bin/activate is Doing It Wrong", but now refers to "Prefer Subshells for Context."
That link, https://datagrok.org/python/activate/, is now 404 not found.
Thankfully, archive.org saved it at https://web.archive.org/web/20201111231240/https://datagrok.org/python/activate/
So the README should probably point there now.
But perhaps someone knows a better more permanent, live page?