input: 
  from typing import List
  
  def sort_words_by_length(my_string: str) -> str:
      """ Sorts words in a given string by their length in decreasing order, then by 
      alphabetical order if lengths are the same.
      >>> sort_words_by_length("This is the string which is to be sorted")
      'string which sorted is to be This the is'
      """
  
output:     words = my_string.split()
      words.sort(key=lambda x: (-len(x), x))
      return ' '.join(words)