def followers_for_story(story):
        topic_set = set(story['topic_list'])
        author_key = story['author_key']

    # Group the author's followers by user_key
        followers = sorted(self.socialgraph.follower_set(author_key))
    followers = groupby(followers,lambda x: x[0])

    # Iterate over each follower
        for follower_key, grouper in followers:
            # Create a topic set for the follower
            follow_topic_set = set(topic for (_, topic) in grouper)

            # If any followed topic is in the story's topic_set,
            # yield the follower_key
            if any((topic in topic_set) for topic in follow_topic_set):
        yield follower_key