code: def join_tokens_to_sentences(tokens):
      
      text = ""
      for (entry, next_entry) in zip(tokens, tokens[1:]):
          text += entry
          if next_entry not in SENTENCE_STOPS:
              text += " "
  
      text += tokens[-1]
      return text
docs: Correctly joins tokens to multiple sentences
  
      Instead of always placing white-space between the tokens, it will distinguish
      between the next symbol and *not* insert whitespace if it is a sentence
      symbol (e.g. '.', or '?')
  
      Args:
          tokens: array of string tokens
      Returns:
          Joint sentences as one string