docs: private static <M extends Model> void findDepth(Hierarchy<Cluster<M>> hier, Cluster<M> cluster, int[] size) {
      if(hier.numChildren(cluster) > 0) {
        for(It<Cluster<M>> iter = hier.iterChildren(cluster); iter.valid(); iter.advance()) {
          findDepth(hier, iter.get(), size);
        }
        size[0] += 1; // Depth
      }
      else {
        size[1] += 1; // Leaves
      }
    }