input: def substring_in_order(string: str) -> List[str]:
      """Generate a Python program which takes a string as input and prints all of its substrings in order from longest to shortest length.
      >>> substring_in_order("abc")
      ['abc', 'ab', 'bc', 'a', 'b', 'c']
      >>> substring_in_order("hello")
      ['hello', 'hell', 'ello', 'hel', 'ell', 'llo', 'he', 'el', 'll', 'lo', 'h', 'e', 'l', 'l', 'o']
      """
output:     substrings = []
      length = len(string)
      for i in range(length):
          for j in range(i + 1, length + 1):
              substrings.append(string[i:j])
      substrings.sort(key=len, reverse=True)
      return substrings