code: def join(tokens, start, result):
      
      texts = []
      if len(result) > 0:
          for e in result:
              for child in e.iter():
                  if child.text is not None:
                      texts.append(child.text)
          return [E(result[0].tag, ' '.join(texts))]
docs: Join tokens into a single string with spaces between.