Convert TypeScript function to Python

I need the function decodeTxRaw() translated from TypeScript to Python.

I am not good at Node/TS, but the task does look a bit complicated since there are a lot of dependencies. The python code must be able to stand on its own.

The function is defined here:
https://github.com/cosmos/cosmjs/blob/main/packages/proto-signing/src/decode.ts

It is part of this package:
https://www.npmjs.com/package/@cosmjs/proto-signing