docs: private DoubleDBIDList subsetNeighborhoodQuery(DoubleDBIDList neighc, DBIDRef dbid, PrimitiveDistanceFunction<? super NumberVector> df, double adjustedEps, KernelDensityEstimator kernel, ModifiableDoubleDBIDList n) {
      n.clear();
      NumberVector query = kernel.relation.get(dbid);
      for(DoubleDBIDListIter neighbor = neighc.iter(); neighbor.valid(); neighbor.advance()) {
        // TODO: use triangle inequality for pruning
        double dist = df.distance(query, kernel.relation.get(neighbor));
        if(dist <= adjustedEps) {
          n.add(dist, neighbor);
        }
      }
      return n;
    }