docs: public void merge(ClusteringFeature x) {
  		assert (this.sumPoints.length == x.sumPoints.length);
  		this.numPoints += x.numPoints;
  		super.setWeight(this.numPoints);
  		for (int i = 0; i < this.sumPoints.length; i++) {
  			this.sumPoints[i] += x.sumPoints[i];
  		}
  		this.sumSquaredLength += x.sumSquaredLength;
  	}