input: Write a python function to combine two lists into a list of tuples.
  assert combine_lists([1, 2, 3], ['a', 'b', 'c']) == [(1, 'a'), (2, 'b'), (3, 'c')]
  assert combine_lists([4, 5], ['d', 'e']) == [(4, 'd'), (5, 'e')]
  assert combine_lists([], []) == []
output: def combine_lists(list1, list2):
      return list(zip(list1, list2))