def fetch_stream_subscriber_user_ids(stream: Stream) -> List[int]:
    if (stream.is_in_zephyr_realm and (not stream.invite_only)):
        return []
    user_ids = all_subscribers_by_stream[stream.id]
    return user_ids
def fetch_stream_subscriber_user_ids(stream: Stream) -> List[int]:
    if (stream.is_in_zephyr_realm and (not stream.invite_only)):
        return []
    user_ids = all_subscribers_by_stream[stream.id]
    return user_ids