input: 
  def dot_product(list1, list2):
      """Calculates the dot product of two input lists.
      >>> dot_product([1, 2], [3, 4])
      11
      >>> dot_product([1, 2, 3], [4, 5, 6])
      32
      """
      product = 0
      for i in range(len(list1)):
          product += (list1[i] * list2[i])
      return product
  
output:     product = 0
      for i in range(len(list1)):
          product += (list1[i] * list2[i])
      return product