code: def speaker_durations(utterances: List[Utterance]) -> List[Tuple[str, int]]:
      
  
      speaker_utters = make_speaker_utters(utterances)
  
      speaker_duration_tuples = [] # type: List[Tuple[str, int]]
      for speaker in speaker_utters:
          speaker_duration_tuples.append((speaker, total_duration(speaker_utters[speaker])))
  
      return speaker_duration_tuples
docs: Takes a list of utterances and itemizes them by speaker, returning a
      list of tuples of the form (Speaker Name, duration).