lst-0093-book.cpp
// https://godbolt.org/z/7h3vsWvYG
map<string,int> dwarves;
dwarves.emplace("Fili", 2859);
cout << dwarves["Fili"] << '\n'; // Output: 2859
cout << dwarves["Dori"] << '\n'; // newly created. Output: 0
dwarves["Kili"] = 2846; // newly created and immediately overwritten
cout << dwarves["Kili"] << '\n'; // Output: 2846
cout <<= dwarves; // Output: Dori:0 Fili:2859 Kili:2846