Returns the list of time zones corresponding to the country calling code of a number.
    Arguments:
    numobj -- the phone number to look up
    Returns a list of the corresponding time zones or a single element list with the default
    unknown time zone if no other time zone was found or if the number was invalid

def _country_level_time_zones_for_number(numobj):
    """Returns the list of time zones corresponding to the country calling code of a number.
    Arguments:
    numobj -- the phone number to look up
    Returns a list of the corresponding time zones or a single element list with the default
    unknown time zone if no other time zone was found or if the number was invalid"""
    cc = str(numobj.country_code)
    for prefix_len in range(TIMEZONE_LONGEST_PREFIX, 0, -1):
        prefix = cc[:(1 + prefix_len)]
        if prefix in TIMEZONE_DATA:
            return TIMEZONE_DATA[prefix]
    return _UNKNOWN_TIME_ZONE_LIST