def add_flag_argument(parser, name, dest=None, default=False, help=None):
    """ Add a flag argument to an ArgumentParser instance.
        Either the --flag is present or the --no-flag is present.
        No trying to convert boolean values like the add_boolean_argument
    """
    if not dest:
        dest = name
    group = parser.add_mutually_exclusive_group()
    bool_help = help + ' Use --no-' + name + ' to turn the feature off.'
    group.add_argument('--' + name, dest=dest, default=default, action=
        'store_true', help=bool_help)
    group.add_argument('--no-' + name, dest=dest, action='store_false',
        default=not default)
