input: 
  def dot_product(list1, list2):
    product = 0
    for i in range(len(list1)):
      product += (list1[i] * list2[i])
    return product
  # Example
  list1 = [1,2]
  list2 = [3,4]
  result = dot_product(list1, list2)
  print(result)
  # Output
  11
  
output:     
    return product
  