def get(self, name: str, sig: Tuple) -> Optional[object]:
        """
        Return the object representing name if it is cached
        :param name: name of object
        :param sig: unique signature of object
        :return: object if exists and signature matches
        """
        if name not in self._cache:
            return None
        if self._cache[name].sig != sig:
            del self._cache[name]
            self._update()
            return None
        with open(self._cache[name].loc, 'rb') as f:
            return pickle.load(f)