std::cout << " <depth>" << std::endl;
std::cout << " <max>" << max_depth << "</max>" << std::endl;
std::cout << " <leaf-avg>" << tot_depth / ((double) n_depths) << "</leaf-avg>" << std::endl;
std::cout << " <depth>" << std::endl;
std::cout << " <max>" << max_depth << "</max>" << std::endl;
std::cout << " <leaf-avg>" << tot_depth / ((double) n_depths) << "</leaf-avg>" << std::endl;