*/
public static RollingWindowSet keyed_avg_rolling_window_set(
int num_buckets, Integer[] bucket_sizes) {
RunnableCallback updater = new KeyAvgUpdater();
RunnableCallback merger = new KeyAvgMerge();
RunnableCallback extractor = new KeyAvgExtractor();
return RollingWindowSet.rolling_window_set(updater, merger, extractor,
num_buckets, bucket_sizes);