def add_ago_to_since(since: str) -> str:
    """
    Backwards compatibility hack. Without this slices with since: 7 days will
    be treated as 7 days in the future.

    :param str since:
    :returns: Since with ago added if necessary
    :rtype: str
    """
    since_words = since.split(" ")
    grains = ["days", "years", "hours", "day", "year", "weeks"]
    if len(since_words) == 2 and since_words[1] in grains:
        since += " ago"
    return since