twenty-four hour clock object with nanosecond precision

 A Time::Clock object is a twenty-four hour clock with nanosecond precision
 and wrap-around. It is a clock only; it has absolutely no concept of dates.
 Vagaries of date/time such as leap seconds and daylight savings time
 are unsupported.
 .
 When a Time::Clock object hits 23:59:59.999999999 and at least one more
 nanosecond is added, it will wrap around to 00:00:00.000000000. This works
 in reverse when time is subtracted.
 .
 Time::Clock objects automatically stringify to a user-definable format.