docs: def summult(list1, list2):
      """
  Multiplies elements in list1 and list2, element by element, and
  returns the sum of all resulting multiplications.  Must provide equal
  length lists.
  
  Usage:   lsummult(list1,list2)
  """
      if len(list1) != len(list2):
          raise ValueError("Lists not equal length in summult.")
      s = 0
      for item1, item2 in zip(list1, list2):
          s = s + item1 * item2
      return s