in #15654, these attributes were made less typesafe by changing their type from IO[AnyStr] to IO[Any]:

from subprocess import PIPE, Popen

with Popen(["echo", "hi"], stdout=PIPE, text=True) as process:
    if process.stdout:
        for line in process.stdout:
            line.asdfasdf # no type error, crashes at runtime

there didn't seem to be any explanation for this change in that PR which is why i'm opening a new issue. is there a reason the types can't be IO[AnyStr]?