def get_meta_data(file_name):
    """Helper function to retrieve a given file name's year, month, and zone.

    Takes a string file_name formatted as ``'AIS_yyyy_mm_Zone##.csv'`` and returns the numerical
    values of ``yyyy, mm, ##`` corresponding to year, month, and zone number as a tuple.

    Args:
        file_name (str): The file name to be parsed in format ``'AIS_yyyy_mm_Zone##.csv'``.

    Returns:
        tuple: The year, month, and zone corresponding to the filename passed in.
    """
    meta_file_data = file_name.split(
        "_"
    )  # splits csv file on '_' character, which separates relevant file info
    year = int(meta_file_data[-3])  # third to last element of file is the year
    month = int(
        meta_file_data[-2]
    )  # second to last element of file is the month

    # get zone number for csv file being read
    ending_raw = meta_file_data[
        -1
    ]  # gets last part of the file, with format "ZoneXX.csv"
    ending_data = ending_raw.split(
        "."
    )  # splits last part of file on '.' character
    zone_raw = ending_data[0]  # gets "ZoneXX" string
    zone_data = zone_raw[
        -2:
    ]  # gets last 2 characters of "ZoneXX" string - will be the zone number
    zone = int(zone_data)

    return year, month, zone