code: def PmfProbLess(pmf1, pmf2):
      
      total = 0.0
      for v1, p1 in pmf1.Items():
          for v2, p2 in pmf2.Items():
              if v1 < v2:
                  total += p1 * p2
      return total
docs: Probability that a value from pmf1 is less than a value from pmf2.
  
      Args:
          pmf1: Pmf object
          pmf2: Pmf object
  
      Returns:
          float probability