input: Write a function to calculate the dot product of two lists.
  assert dot_product([1, 2], [3, 4]) == 11
  assert dot_product([1, 0, -1], [4, 5, -6]) == 10
  assert dot_product([0, 0, 0], [1, 2, 3]) == 0
  assert dot_product([1, 2, 3], [4, 5, 6]) == 32
output: def dot_product(list1, list2):
      return sum(a * b for a, b in zip(list1, list2))