input: def get_all_substrings_reversed(s: str) -> List[str]:
      """Generate all substrings of a given string in order from longest to shortest.
      >>> get_all_substrings_reversed("abc")
      ['abc', 'ab', 'bc', 'a', 'b', 'c']
      >>> get_all_substrings_reversed("xyz")
      ['xyz', 'xy', 'yz', 'x', 'y', 'z']
      """
      substrings = []
      for length in range(len(s), 0, -1):
          for start in range(len(s) - length + 1):
              substrings.append(s[start:start + length])
      return substrings
output:     substrings.reverse()
      return substrings