#include <iostream>
#include <string>

struct Logger
{
    std::string header;
    Logger(std::string h) : header(h) {}

    friend std::ostream& operator<<(std::ostream& os, const Logger& log)
    {
        os << log.header;
        return os;
    }
};

int main()
{
    Logger t("INFO: ");
    std::cout << t << "AB:CD:EF:12:34:56 associated\n";
    return 0;
}