default Tensor rename(String fromDimension, String toDimension) {
        return new Rename<>(new ConstantTensor<>(this), List.of(fromDimension),
                                                        List.of(toDimension)).evaluate();
    }
Aggregates cells over a set of dimensions, or over all dimensions if no dimensions are specified
vespajlib/src/main/java/com/yahoo/tensor/Tensor.java