def METHOD_NAME():
    """The main function. Hier spielt die Musik.
    """
    # parse the command line, exit with UNKNOWN if it fails
    try:
        args = parse_args()
    except SystemExit:
        sys.exit(STATE_UNKNOWN)
    # fetch data
    if args.TEST is None:
        # Do NOT use `timedatectl show` if you want to be compatible to older
        # systemd versions, as this is only available since 2018-05 (and therefore not on RHEL 7).
        # Use `timedatectl status` instead.
        cmd = 'timedatectl status'
        stdout, stderr, retc = lib.base.coe(lib.shell.shell_exec(cmd)) # pylint: disable=W0612
        if stderr:
            lib.base.oao('{}'.format(stderr), STATE_WARN)
    else:
        # do not call the command, put in test data
        stdout, stderr, retc = lib.test.test(args.TEST)
    # init some vars
    msg = ''
    state = STATE_OK
    # analyze data and build the message
    # i->ntp_synced
    msg += lib.txt.extract_str(stdout, 'NTP synchronized: ', '\n', include_fromto=True).replace('\n', ', ')
    msg += lib.txt.extract_str(stdout, 'System clock synchronized: ', '\n', include_fromto=True).replace('\n', ', ')
    # yes_no(i->ntp), i->ntp_capable
    msg += lib.txt.extract_str(stdout, 'NTP enabled: ', '\n', include_fromto=True).replace('\n', ', ')
    msg += lib.txt.extract_str(stdout, 'systemd-timesyncd.service active: ', '\n', include_fromto=True).replace('\n', ', ')
    msg += lib.txt.extract_str(stdout, 'NTP service: ', '\n', include_fromto=True).replace('\n', ', ')
    msg = msg[:-2]
    if 'RTC in local TZ: yes' in stdout:
        state = STATE_WARN
        msg += '. The system is configured to read the RTC time in the local time zone. ' \
               'This mode cannot be fully supported. It will create various problems ' \
               'with time zone changes and daylight saving time adjustments. The RTC ' \
               'time is never updated, it relies on external facilities to maintain it. ' \
               'If at all possible, use RTC in UTC by calling ' \
               '`timedatectl set-local-rtc 0`{}.'.format(
            lib.base.state2str(state, prefix=' '),
        )
    else:
        msg += ', RTC in local TZ: no'
    # over and out
    lib.base.oao(msg, state, always_ok=args.ALWAYS_OK)