code: def extract_wavs(utterances: List[Utterance], tgt_dir: Path,
                   lazy: bool) -> None:
      
      tgt_dir.mkdir(parents=True, exist_ok=True)
      for utter in utterances:
          wav_fn = "{}.{}".format(utter.prefix, "wav")
          out_wav_path = tgt_dir / wav_fn
          if lazy and out_wav_path.is_file():
              logger.info("File {} already exists and lazy == {}; not " \
                           "writing.".format(out_wav_path, lazy))
              continue
          logger.info("File {} does not exist and lazy == {}; creating " \
                       "it.".format(out_wav_path, lazy))
          trim_wav_ms(utter.org_media_path, out_wav_path,
                      utter.start_time, utter.end_time)
docs: Extracts WAVs from the media files associated with a list of Utterance
      objects and stores it in a target directory.
  
      Args:
          utterances: A list of Utterance objects, which include information
              about the source media file, and the offset of the utterance in the
              media_file.
          tgt_dir: The directory in which to write the output WAVs.
          lazy: If True, then existing WAVs will not be overwritten if they have
              the same name