Question on time module

[subhabrata.iisc at hotmail.com]

Dear Members of the group,
I have one function
def sum1(n):
      a1=5
      a2=6
      a3=a1+a2
      a4=a3+8
      print "The First sum is"
      print a3
      print "The Second sum is"
      print a4

Now, I want to do it in a way, a4 is calculated after a given time
interval of a3 -this is easy but if I want to check after how much
time a4 is calculated from a3 how can I do?
If any one can help it.
Best Regards,
Subhabrata.