docs: protected static <M extends Model> int[] findDepth(Clustering<M> c) {
      final Hierarchy<Cluster<M>> hier = c.getClusterHierarchy();
      int[] size = { 0, 0 };
      for(It<Cluster<M>> iter = c.iterToplevelClusters(); iter.valid(); iter.advance()) {
        findDepth(hier, iter.get(), size);
      }
      return size;
    }