How to get a DateTime::SpanSet duration in seconds for doing math?

Hi, I'm trying to find a way to perform math with the duration of a
DateTime::SpanSet. I'd prefer it to be in seconds, but I can't find
anything from it in the documentation.

What I did find is that the DateTime module has a
*subtract_datetime_absolute* function that would give me seconds and
nanoseconds from two DateTime objects.
So I guess one way to do this is to iterate over the entire
DateTime::SpanSet, and for all DateTime::Span
perform subtract_datetime_absolute for the start and end of it, and sum it
all. I haven't tried this yet tho..

Would this approach work, or is there any other better way?

Kind regards,
Andreas Isberg
Telefon: 072-588 91 95