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:
        # for `exim`, `mailq` is an alias for `exim -bq`
        stdout, stderr, retc = lib.base.coe(lib.shell.shell_exec('mailq'))
    else:
        # do not call the command, put in test data
        stdout, stderr, retc = lib.test.test(args.TEST)
    mailq_err_msg = None
    if stderr:
        # does mailq report something unusual?
        mailq_err_msg = stderr.strip()
    # count the mails in the queue
    mailq_count = 0
    stdout = stdout.strip()
    if stdout and stdout != 'Mail queue is empty' and stdout != '0 mails to deliver':
        # "-- 2 Kbytes in 3 Requests."
        mailq_count = re.search(r' in (.*) Requests?\.', stdout)
        if mailq_count:
            mailq_count = int(mailq_count.group(1).strip())
        else:
            # other mailq version? "17 mails to deliver"
            mailq_count = re.search(r'(.*) mails to deliver', stdout)
            if mailq_count:
                mailq_count = int(mailq_count.group(1).strip())
            else:
                # exim? for now, just count the lines (could be done better in the future)
                mailq_count = stdout.count('\n')
    # init some vars
    msg = ''
    perfdata = ''
    if mailq_err_msg:
        msg += '{}. '.format(mailq_err_msg)
    if mailq_count:
        msg += '{} {} to deliver.'.format(mailq_count, lib.txt.pluralize('mail', mailq_count))
    else:
        msg += 'Mail queue is empty.'
    perfdata += lib.base.get_perfdata('mailq', mailq_count, None, args.WARN, args.CRIT, 0, None)
    state = lib.base.get_state(mailq_count, args.WARN, args.CRIT, _operator='ge')
    if mailq_err_msg:
        state = lib.base.get_worst(state, STATE_WARN)
    # over and out
    lib.base.oao(msg, state, perfdata, always_ok=args.ALWAYS_OK)