wiki/nest-asyncio/README.md

''
import asyncio
(loop := asyncio.get_event_loop()).__class__._check_running = lambda _: None
def _run_once(self):
    self._process_events(self._selector.select(0))
    if (ready := self._ready) and not (handle := ready.popleft())._cancelled:
        task = (tasks := asyncio.tasks._current_tasks).pop(self, None)
        handle._run()
        tasks[self] = task
loop.__class__._run_once = _run_once
asyncio.run = loop.run_until_complete
''
async def hello():
    async def world(): print('hello')
    asyncio.run(world()) or print('world')
asyncio.run(hello()) # OK
''