In this case:

```python3
class A:
    async def close(self):
        pass
    
with closing(A()):
    pass
```

Python will raise `RuntimeWarning: coroutine 'A.close' was never awaited`.

In another case:

```python3
class B:
    def close(self):
        pass
    
async with closing(B()):
    pass
```

Python will raise `TypeError: object NoneType can't be used in 'await' expression` (because it will try to await result of close method).

-----

I was surprised that `contextlib` has no async analogue of this `closing` class, because async scripts often use any kind of closings. Do you think it's better to extract to `asyncclosing` class?