input: Write a function that combines two strings and then reverses the combined result in Python. The function should accept two parameters, both strings, and return the reversed combined string. Here is the function header: `def reverse_combined_strings(s1, s2)`.
  
  
  def reverse_combined_strings(s1, s2):
      combined = s1 + s2
      result = combined[::-1]
      return result
  
  
  Here are the assert test cases to verify the function:
  
  
  assert reverse_combined_strings("Hello ", "world!") == "!dlrow olleH"
  assert reverse_combined_strings("open", "ai") == "ianepo"
  assert reverse_combined_strings("", "test") == "tset"
  assert reverse_combined_strings("a", "b") == "ba"
  assert reverse_combined_strings("", "") == ""
  
output: def reverse_combined_strings(s1, s2):
      combined = s1 + s2
      result = combined[::-1]
      return result