F821 with Annotated import alias

We have a use-case where we sometimes import Annotated under a different name (since there is a naming collision with an existing object callled Annotations and Annotated[Annotations, ...] can be hard to read. Unfortunately, it looks like if we try to do this, then we fail with a false positive:

from typing_extensions import Annotated as WithSchema


def f(x: WithSchema[int, "hello"]) -> None:
    return

fails pyflakes with F821 undefined name 'hello.

Everything works fine if we do not use the Annotated as WithSchema import alias though. Would it be possible to extend the logic to also handle such a case?

cc @nishkakar @ezrilow

No source files or tests are named in the issue. First reproduce the F821 warning with the provided Annotated as WithSchema example, then trace pyflakes' handling of Annotated imports and aliases. Done means the aliased example no longer reports the string literal as an undefined name while existing behavior remains intact.