This code behaves differently when PYTHONASYNCIODEBUG=1

import asyncio
import inspect


@asyncio.coroutine
def foo():
    yield from asyncio.sleep(0)


print("isgeneratorfunction:", inspect.isgeneratorfunction(foo))


PYTHONASYNCIODEBUG:
isgeneratorfunction: False

non-debug mode:
isgeneratorfunction: True


When in debug mode, the `asyncio.coroutine` decorator returns a function that is not a generator function (https://github.com/python/cpython/blob/bd4a3f21454a6012f4353e2255837561fc9f0e6a/Lib/asyncio/coroutines.py#L144)

The result is that introspection of functions is changed when PYTHONASYNCIODEBUG is enabled.

asyncio.coroutine was removed in 3.11, and I don't think this will be changed in stable versions. I will close this issue unless I am corrected.

Agree, thanks!