input: Write a function to combine the elements of two lists into a list of tuples. If the lengths of the two lists are not equal, the function should return a ValueError.
  assert combine_list([1, 2, 3], [4, 5, 6])==[(1, 4), (2, 5), (3, 6)]
  assert combine_list([1, 2], [3, 4, 5])==ValueError
  assert combine_list([], [])==[]
  assert combine_list(['a', 'b'], [10, 20])==[('a', 10), ('b', 20)]
output: def combine_list(list1, list2):
      if len(list1) != len(list2):
          raise ValueError
      return list(zip(list1, list2))