#include <iostream>
#include <sstream>
using namespace std;
int main(){
ostringstream oss;
oss << "captured: [";
auto cout_buff = cout.rdbuf(oss.rdbuf());
cout << "\nHello world";
cout.rdbuf(cout_buff);
oss << "]";
string n = oss.str();
cout << n;
return 0;
}
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