Parse commandline arguments.

def parse_arguments():
    """
    Parse commandline arguments.
    """

    parser = argparse.ArgumentParser()

    # Add options
    parser.add_argument(
        "-n", "--number", action="store", default=1000000, type=int,
        help="number of items")
    parser.add_argument(
        "-p", "--pause", action="store_true", help="pause after execution")

    # Parse command line
    return parser.parse_args(), parser