def METHOD_NAME(time_zone_id: str) -> int:
    # Doesn't deal with DST. We will be conservative and only trade 1 hour
    # after and 1 hour before
    # confusingly, IB seem to have changed their time zone codes in 2020
    # some of these are legacy codes which could be removed
    time_diff_dict = {
        "CST (Central Standard Time)": 6,
        "MET (Middle Europe Time)": -1,
        "EST (Eastern Standard Time)": 5,
        "JST (Japan Standard Time)": -9,
        "US/Eastern": 5,
        "MET": -1,
        "EST": 5,
        "JST": -9,
        "Japan": -9,
        "US/Central": 6,
        "GB-Eire": 0,
        "Hongkong": -8,
        "Australia/NSW": -11,
        "": 0,
    }
    GMT_offset_hours = get_GMT_offset_hours()
    for k, v in time_diff_dict.items():
        time_diff_dict[k] = v + GMT_offset_hours
    diff_hours = time_diff_dict.get(time_zone_id, None)
    if diff_hours is None:
        raise Exception("Time zone '%s' not found!" % time_zone_id)
    return diff_hours