Similar to TimeofDay , the Time::SuperTimeRange
has a number of methods for digging out time parts of the
range. Since a SuperTimeRange is a bit more
complex - the major reason for its existance it that it
contains holes, this calculation is a bit more advanced too.
If a range contains the seconds, say, 1..2 and 4..5,
the third second (number 2, since we start from 0)
in the range would be number 4, like this:
no means this second
0 1
1 2
2 4 <- second three is missing,
3 5 as we don't have it in the example range
number_of_seconds () will in this example
therefore also report 4, not 5, even if the time from
start of the range to the end of the range is 5 seconds.