This year, if it's December.
    The most recent year, otherwise.
    Note: Advent of Code started in 2015

def most_recent_year():
    """
    This year, if it's December.
    The most recent year, otherwise.
    Note: Advent of Code started in 2015
    """
    aoc_now = datetime.datetime.now(tz=AOC_TZ)
    year = aoc_now.year
    if aoc_now.month < 12:
        year -= 1
    if year < 2015:
        raise AocdError("Time travel not supported yet")
    return year