def add_args(parser):
    """Adds vlog related options to 'parser', an ArgumentParser object.  The
    resulting arguments parsed by 'parser' should be passed to handle_args."""
    group = parser.add_argument_group(title='Logging Options')
    group.add_argument('--log-file', nargs='?', const='default', help=
        'Enables logging to a file.  Default log file is used if LOG_FILE is omitted.'
        )
    group.add_argument('-v', '--verbose', nargs='*', help=
        'Sets logging levels, see ovs-vswitchd(8).  Defaults to dbg.')
