Parse arguments.

def parse_args():
    """Parse arguments."""
    parser = argparse.ArgumentParser(
        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
        description='Diagnose script for checking the current system.')
    choices = ['python', 'pip', 'mxnet', 'os', 'hardware', 'network']
    for choice in choices:
        parser.add_argument('--' + choice, default=1, type=int,
                            help='Diagnose {}.'.format(choice))
    parser.add_argument('--region', default='', type=str,
                        help="Additional sites in which region(s) to test. \
                        Specify 'cn' for example to test mirror sites in China.")
    parser.add_argument('--timeout', default=10, type=int,
                        help="Connection test timeout threshold, 0 to disable.")
    args = parser.parse_args()
    return args