-parser.add_argument('-m', type=int, default=45,
- help="main time in minutes")
+parser.add_argument('-m', type=int, default=10,
+ help="main time in minutes (default is 10)")
+parser.add_argument('-b', type=int, nargs=2, default=[5, 20],
+ help="japanese byoyomi: number of periods, period length in"
+ " seconds (default is 5 periods, 20 seconds)")