for (const auto &key_and_value : double_metrics) {
if (key_and_value.second.type == TYPE_GAUGE) {
ss << "# TYPE nageru_" << key_and_value.first << " gauge\n";
for (const auto &key_and_value : double_metrics) {
if (key_and_value.second.type == TYPE_GAUGE) {
ss << "# TYPE nageru_" << key_and_value.first << " gauge\n";