code: def set_store_to(self, store_to):
          
          assert store_to is None or isinstance(store_to, Cache), \
              "store_to needs to be None or a Cache object."
          assert store_to is None or store_to.cl_size <= self.cl_size, \
              "cl_size may only increase towards main memory."
          self.store_to = store_to
          self.backend.store_to = store_to.backend
docs: Update store_to in Cache and backend.