defer-like rollback in python

python_rollback.py

import asyncio
from contextlib import AsyncExitStack

async def a():
    print('step A')

async def roll_a():
    print('rollback step A')

async def b():
    print('step B')

async def roll_b():
    print('rollback step B')

async def test():
    async with AsyncExitStack() as stack:
        await a()
        stack.push_async_exit(lambda *exc: roll_a())

        await b()
        stack.push_async_exit(lambda *exc: roll_b())

        stack.pop_all()

loop = asyncio.get_event_loop()
loop.run_until_complete(test())