code: def first_older_than_second(version_a, version_b):
          
  
          a = nssversion.to_ints(version_a)
          b = nssversion.to_ints(version_b)
  
          # must be of equal length
          assert len(a) == len(b)
  
          # Compare each version component, bail out on difference
          for i in xrange(len(a)):
              if b[i] < a[i]:
                  return False
              if b[i] > a[i]:
                  return True
          return False
docs: Tests for the NSS version string in the first parameter being less
          recent than the second (a < b). Tag order is RTM > RC > BETA > *.
          Works with hg tags like "NSS_3_7_9_RTM" and version strings reported by
          nsINSSVersion, like "3.18 Basic ECC Beta" (mixed, too).
          :param version_a: a NSS version string
          :param version_b: another NSS version string
          :return: bool (a < b)