The import was working around the fact "tuple[T]" was used instead of
typing.Tuple[T].

Convert it to use type.Tuple to be consistent with how the rest of the
code is anotated.
Signed-off-by: NDaniel Latypov <dlatypov@google.com>
Reviewed-by: NDavid Gow <davidgow@google.com>
Reviewed-by: NBrendan Higgins <brendanhiggins@google.com>
Tested-by: NBrendan Higgins <brendanhiggins@google.com>
Signed-off-by: NShuah Khan <skhan@linuxfoundation.org>