code: def distinct_words(string_matrix: List[List[str]]) -> Set[str]:
      
      return set([word
                  for sentence in string_matrix
                  for word in sentence])
docs: Diagnostic function
      :param string_matrix:
      :return:
      >>> dl = distinct_words([['the', 'quick', 'brown'], ['here', 'lies', 'the', 'fox']])
      >>> sorted(dl)
      ['brown', 'fox', 'here', 'lies', 'quick', 'the']