#includeIn this example, we create a StringBuilder object called `builder` with an initial capacity of 1 GB. We then append some strings to the builder using the `<<` operator, before finally printing out the full string using the `str()` method. It is difficult to determine the package library from this example without additional context, but it is likely part of the standard C++ library.#include #include int main() { std::stringstream builder; builder.str().reserve(1000000000); // allocate 1 GB of memory // append some strings to the builder builder << "Hello, "; builder << "world!"; builder << std::to_string(123); std::cout << builder.str() << std::endl; return 0; }