saved_model->variable_reader()->Lookup(checkpoint_key, &value),
            "Could not read checkpoint key from variables bundle: ",
            checkpoint_key);
        TF_ASSIGN_OR_RETURN(auto value_attr, ConvertTensor(value, &builder));
        // A variable can have a partially known type, such as
        // tensor<?x27x?xf32>, even if the initializer is a specific static
        // shape.