@Override
    public String toString() {
        StringBuilder sb = new StringBuilder("cell address (");
        int size = size();
        if (size > 0) {
            sb.append(label(0));
            for (int i = 1; i < size; i++) {
                sb.append(',').append(label(i));
            }
        }

        return sb.append(')').toString();
    }
Returns the i'th label in this as a long.
Prefer this if you know that this is a numeric address, but not otherwise.

@throws IllegalArgumentException if there is no label at this index
vespajlib/src/main/java/com/yahoo/tensor/TensorAddress.java