input: def combine_and_reverse(first: str, second: str) -> str:
      """ Combine two given strings and reverse the result.
      >>> combine_and_reverse("Hello ", "world!")
      '!dlrow olleH'
      >>> combine_and_reverse("Python", " is fun!")
      '!nuf si nohtyP'
      """
output:     combined = first + second
      return combined[::-1]