three_months_commenters = Counter[str]()
    six_months_commenters = Counter[str]()
    one_year_commenters = Counter[str]()
    authors: dict[str, Author] = {}

    now = datetime.now(tz=timezone.utc)
    one_month_ago = now - timedelta(days=30)
    three_months_ago = now - timedelta(days=90)
    six_months_ago = now - timedelta(days=180)
    one_year_ago = now - timedelta(days=365)