How to use the argparse.Const.OPTIONAL function in argparse

help: 'foo bar',
        nargs: Const.ONE_OR_MORE
    }
);
constExample.addArgument(
    ['-b', '--bar'],
    {
        help: 'bar foo',
        nargs: Const.ZERO_OR_MORE
    }
);
constExample.addArgument(
    '--baz',
    {
        help: 'baz',
        nargs: Const.OPTIONAL
    }
);
constExample.addArgument(
    '--qux',
    {
        help: Const.SUPPRESS
    }
);
constExample.addArgument(
    'quux',
    {
        help: 'quux',
        nargs: Const.REMAINDER
    }
);