code: public Histogram newMaxDiffFreqHistogram(int numBkts, int numPcts) {
  		Map<String, BucketBuilder> initBbs = new HashMap<String, BucketBuilder>();
  		// initialize the first bucket builder for every field
  		for (String fld : schema.fields())
  			initBbs.put(fld, new MaxDiffFreqBucketBuilder(frequencies(fld),
  					numPcts));
  		return newMaxDiffHistogram(numBkts, initBbs);
  	}
docs: Constructs a histogram with the "MaxDiff(V, F)" buckets for all fields.
  
  @param numBkts
  the number of buckets to construct for each field
  @param numPcts
  the number of value percentiles in each bucket
  @return a "MaxDiff(V, F)" histogram