docs: def is_older_than_metadata(self):
          """
          Return True if the package save file is older than the metadata. If it is, it should be rebuilt.  Returns
          False if the time of either can't be determined
  
          :param path: Optional extra save path, used in save_path()
  
          """
  
          try:
              path = self.doc_file.path
          except AttributeError:
              path = self.doc_file
  
          source_ref = self._doc.ref.path
  
          try:
              age_diff = getmtime(source_ref) - getmtime(path)
  
              return age_diff > 0
  
          except (FileNotFoundError, OSError):
              return False