def _num_to_month(num):
    """Helper function to convert month number to short name

    Args:
        num (int): the month number to convert

    Returns:
        (str): The three letter short name of the corresponding month

    """

    return {
        1: "Jan",
        2: "Feb",
        3: "Mar",
        4: "Apr",
        5: "May",
        6: "Jun",
        7: "Jul",
        8: "Aug",
        9: "Sep",
        10: "Oct",
        11: "Nov",
        12: "Dec",
    }[num]