<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def cycle_find_app(_parser, cmd, args):
 # pragma: no cover """ Find the first position of a value in a de Bruijn sequence. """


    parser = argparse.ArgumentParser(
        prog=_parser.prog,
        description=_parser.description,
    )
    parser.add_argument('-w', '--width', type=int, default=4, help='the length of the cycled value')
    parser.add_argument('value', help='the value to determine the position of, read from stdin if missing', nargs='?')
    args = parser.parse_args(args)
    index = cycle_find(pwnypack.main.string_value_or_stdin(args.value), args.width)
    if index == -1:
        print('Not found.')
        sys.exit(1)
    else:
        print('Found at position: %d' % index)