if (keys.length === 1 && buckets[i][keys[0]].buckets && keys[0].indexOf('NESTED') === -1) {
                const partialList = CSVSerializer.serializeBucket(keys[0], buckets[i][keys[0]].buckets);
                for (let j = 0, { length: partialListLength } = partialList; j < partialListLength; j += 1) {
                    partialList[j][alias] = buckets[i].key;
                }