input: 
  def sort_words_by_length_and_alphabetically(my_string: str) -> str:
      """ Sorts words in a given string by their length in decreasing order and, 
      for words of the same length, alphabetically.
      >>> sort_words_by_length_and_alphabetically("This is the string which is to be sorted")
      'be which to the This is sorted string'
      """
  
output:     words = my_string.split()
      words.sort(key=lambda x: (-len(x), x))
      return ' '.join(words)