@Override
        public Cell next() {
            if ( ! hasNext()) throw new NoSuchElementException("No cell at " + indexes);
            count++;
            indexes.next();
            reusedCell.value = get(indexes.toSourceValueIndex());
            return reusedCell;
        }
Returns the next cell, which is valid until next() is called again
vespajlib/src/main/java/com/yahoo/tensor/IndexedTensor.java