[ang_cire]

This is very cool, and I did not know this. Thank you!

I wonder if my formal university python training predated this change (~2010), or if the professors were themselves unaware of this.

[pjmlp]

They were unaware of it, or unwilling to talk about it, article from 2002, about changes introduced in 2001

https://gnosis.cx/publish/programming/metaclass_1.html

https://www.python.org/download/releases/2.2/descrintro/