docs: @Override
  	public boolean addChild(ClusteringTreeNode e) {
  		assert (this.projections.get(0).length == e.getClusteringFeature()
  				.getCenter().length);
  		super.addChild(e);
  		Iterator<double[]> iIterProjections = this.projections.iterator();
  		Iterator<CuckooHashing<List<ClusteringTreeNode>>> iIterBuckets = this.buckets
  				.iterator();
  		int size = this.projections.size();
  		for (int i = 0; i < size; i++) {
  			long bucketNumber = calcBucketNumber(project(e.getCenter(),
  					iIterProjections.next()));
  			CuckooHashing<List<ClusteringTreeNode>> currentBuckets = iIterBuckets
  					.next();
  			List<ClusteringTreeNode> bucket = currentBuckets.get(bucketNumber);
  			if (bucket == null) {
  				bucket = new ArrayList<ClusteringTreeNode>(1);
  				currentBuckets.put(bucketNumber, bucket);
  			}
  			bucket.add(e);
  		}
  		return true;
  	}