input: Write a function to combine two given strings and reverse the resulting string in Python. Return the reversed string.
  assert reverse_and_combine("Hello ", "world!")=="!dlrow olleH"
  assert reverse_and_combine("Python ", "Rocks!")=="!skcoR nohtyP"
  assert reverse_and_combine("OpenAI ", "ChatGPT!")=="!TGPtahC IAnepO"
  assert reverse_and_combine("Good ", "Morning!")=="!gninroM dooG"
  assert reverse_and_combine("123 ", "456!")=="!654 321"
output: def reverse_and_combine(str1, str2):
      combined = str1 + str2
      return combined[::-1]