Summary of discussion at https://github.com/python-trio/trio/issues/1208:

* `asyncio.Stream.write()` will start throwing a `DeprecationWarning` asking people to add an `await` if they didn't;

* `asyncio.Stream.close()` will start throwing a `DeprecationWarning` asking people to add an `await` if they didn't;

* `asyncio.Stream.drain()` & `asyncio.Stream.wait_closed()` will start throwing a `DeprecationWarning` telling about a scheduled removal (in Python 3.12) when used on `Process.std*` streams;

* `asyncio.Stream.drain()` & `asyncio.Stream.wait_closed()` will not work at all on Streams created via new 3.8 APIs: `connect()` & `StreamServer`.