Q: what was the base firmware for this patch 
A: model-samples_OS1.13.syx the one from May 26, 2021

Q: How do I use the .py file?
A: If you don't know, then back away slowly. 
It's way to early in the firmware modding exploration to be playing around with this, you could lockup/brick your device! 

This is delibarately obtuse so anyone that does manage to use the .py file to patch their section_3_MAIN_OS.bin (something that you need to get by compiling  https://github.com/mischa85/elektron-firmware-tool/ to extract and re-insert the modded file) should know enough to know how dangerious playing with modded firmware that has not extensively been tested can be! 

I'm not responsible for any damage you do to your hardware or data loss if you decide to play around with the above.