code: def _extract_dir(self, dir_not_exists, output):
      
      if not dir_not_exists:
          lst = output.dir_cache
          return {i["relpath"]: i["md5"] for i in lst}
      return {}
docs: Extract the content of dvc tree file
      Args:
          self(object) - Repo class instance
          dir_not_exists(bool) - flag for directory existence
          output(object) - OutputLOCAL class instance
      Returns:
          dict - dictionary with keys - paths to file in .dvc/cache
                                 values -checksums for that files