code: @Override
  	public void accumulateClusterIdsFromInterval(
  			TimeInterval interval, 
  			List<Integer> clusterIds, 
  			NowReference now) throws Exception {
  		
  		if( this.interval.intersectsWith(interval, now) ){
  			clusterIds.add(this.clusterId);
  			
  			if( null != lowChildNode ){
  				lowChildNode.accumulateClusterIdsFromInterval(interval, clusterIds, now);
  			}
  			if( null != highChildNode ){
  				highChildNode.accumulateClusterIdsFromInterval(interval, clusterIds, now);
  			}
  		}
  	}
docs: Find all nodes that intersect with the given interval and accumulate the
  node identifiers (cluster ids) in a provided list.
  @param interval Interval that is requested
  @param clusterIds List of cluster ids that match the given interval
  @throws Exception