(WIP) An In-Game Python Interpreter

This is Leather Sword, a world full of features.
The pack is far from complete, so do not put it into actual use.
The purpose I publish the pack is to share the code along with my thought.

DEBUGGING USAGE
write expressions using only the following operators in a Book & Quill and put it in the inventory #0:
+,-,*,//,%,=,+=,-=,*=,//=,%=
use /scoreboard to add initial variables, and run /function py:run to run the code.

EXAMPLE
/scoreboard players set a data 1
then input "b=a+1" in the book.
Result: b = 2 in scoreboard data

https://www.bilibili.com/video/BV1ARVwzhE3M/
https://www.bilibili.com/video/BV1ZNVqzDEfF/

NOTE
If the process terminates halfway, please adjust the game rule MaxCommandChainLength.