Ask HN: Examples of meta programming or AST-hacking in Python?

I've found a few promising examples of AST-hacking within Python, but I'd like to know if anyone has some more.

Here's what I've found:

http://blaag.haard.se/Using-the-AST-to-hack-constants-into-Python/

http://hackflow.com/blog/2015/03/29/metaprogramming-beyond-decency/

I'd also be interested in just seeing people implementing domain specific languages in Python, using Pyparsing or other techniques.