#include <iostream>
 
class MyLogger {
public:
    MyLogger(std::ostream& logStream) 
    : logStream_(logStream)
    {}
 
    template<typename T>
    friend MyLogger& operator<<(MyLogger&, const T&);
private:
    std::ostream&  logStream_;
};
 
template<typename T>
MyLogger& operator<<(MyLogger& log, const T& value) {
    log.logStream_ << value;
    return log;
}
 
int main() {
    MyLogger log(std::cout);
 
    log << "Hello" << " World!";
}
 

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