def pubsubhub_data(channel_id: str, verify_token: str, mode: str = "subscribe"):
    """returns a dict containing the data needed for a POST to pubsubhubbub.
    """
    data = {
        "hub.callback": "https://discordsubhub.herokuapp.com/pubsubhubbub",
        "hub.topic": f"https://www.youtube.com/xml/feeds/videos.xml?channel_id={channel_id}",
        "hub.verify": "async",
        "hub.mode": mode,
        "hub.verify_token": verify_token,
    }

    return data