Generate a de Bruijn sequence of a given length.

def cycle_app(parser, cmd, args):  # pragma: no cover
    """
    Generate a de Bruijn sequence of a given length.
    """

    parser.add_argument('-w', '--width', type=int, default=4, help='the length of the cycled value')
    parser.add_argument('length', type=int, help='the cycle length to generate')
    args = parser.parse_args(args)
    return cycle(args.length, args.width)