Type hint asyncio.Process streams (stdin, stdout, stderr) when created with values other than default None

Is it possible to update asyncio stub files so that asyncio.Process.{stdin,stdout,stderr} are resolved as non-None by mypy?

Example:

from asyncio import create_subprocess_exec
from asyncio.subprocess import PIPE

async def main() -> None:
    proc = await create_subprocess_exec('/usr/bin/ls', stdout=PIPE)
    async for line in proc.stdout:
        print(line)

Typing error reported by mypy (desired behaviour is no error):

error: Item "None" of "StreamReader | None" has no attribute "__aiter__" (not async iterable)  [union-attr]

Current asyncio.Process declaration in typeshed/stdlib/asyncio/subprocess.pyi:

class Process:
    stdin: streams.StreamWriter | None
    stdout: streams.StreamReader | None
    stderr: streams.StreamReader | None

Commencez par la déclaration de Process dans typeshed/stdlib/asyncio/subprocess.pyi et suivez les déclarations de sous-processus asyncio utilisées par create_subprocess_exec. Reproduisez l’erreur mypy de l’exemple de l’issue, puis vérifiez que le fait de passer PIPE rend les attributs de flux concernés non optionnels sans modifier le comportement par défaut de None.