Return date from epiweek (starts at Sunday)

def epiweek_to_date(ew: Epiweek) -> datetime.date:
    """
    Return date from epiweek (starts at Sunday)
    """

    day_one = _start_date_of_year(ew.year)
    diff = 7 * (ew.week - 1) + (ew.day - 1)

    return day_one + datetime.timedelta(days=diff)