docs: def ReadPathInfo(self, client_id, path_type, components, timestamp=None):
      """Retrieves a path info record for a given path."""
      try:
        path_record = self.path_records[(client_id, path_type, components)]
        return path_record.GetPathInfo(timestamp=timestamp)
      except KeyError:
        raise db.UnknownPathError(
            client_id=client_id, path_type=path_type, components=components)