Using a time duration to print out data where every 2 seconds is a pixel

[cjt22 at bath.ac.uk]

Thanks however I am still having a problem using the time module for
arithmetic

My string times are of values such as 09:55:17

and I have code such as:

>from time import *
>startPoint = strptime(step.sTime, "%H:%S:%M")
>finishPoint = strptime(step.fTime, "%H:%S:%M")

>duration = mktime(startPoint) - mktime(finishPoint)

but it generates the error

>OverflowError: mktime argument out of range

Cheers