wiki/nest-asyncio

import asyncio
def _run_once(loop):
    loop._process_events(loop._selector.select(0))
    if (ready := loop._ready) and (handle := ready.popleft())._cancelled is False:
        task = (tasks := asyncio.tasks._current_tasks).pop(loop, None)
        handle._run(); tasks[loop] = task
(loop := asyncio.get_event_loop()).__class__._run_once = _run_once
asyncio.run = loop.run_until_complete; loop.__class__._check_running = lambda _: 0

async def hello():
    print('hello')
    async def world(): 
        print('world')
    asyncio.run(world())
asyncio.run(hello())
"""
hello
world
"""