Parse the args using the config_file pattern

    Args:
        args: sys.argv

    Returns:
        The populated namespace object from parser.parse_args().

    Raises:
        TBD

def parse_config(args=sys.argv):
    """Parse the args using the config_file pattern

    Args:
        args: sys.argv

    Returns:
        The populated namespace object from parser.parse_args().

    Raises:
        TBD
    """
    parser = argparse.ArgumentParser(
        description='Read in the config file')
    parser.add_argument(
        'config_file',
        help='Configuration file.',
        metavar='FILE', type=extant_file)
    return parser.parse_args(args[1:])