static bool set_dump(std::set<T>& s)
{
std::cout << "set address:" << &s << std::endl;
std::cout << "empty():" << s.empty() << std::endl;
std::cout << "size():" << s.size() << std::endl;
std::cout << "max_size():" << s.max_size() << std::endl;
std::cout << std::endl;
return true;
}
