BernardIE5317 - 2023-02-17

Greetings Kind Regards re/ the code below take from the boost site https://www.boost.org/doc/libs/1_81_0/doc/html/program_options/tutorial.html#id-1.3.30.4.3
i am attempting to find documentation re/ the .as<int>() method near the bottom . it is called on a return from program_options::variables_map.operator [] which as near as i can discern returns an any<> type . however i could find no reference to as in boost documentation . Please advise Thank You Kindly

namespace po = boost::program_options;
// Declare the supported options.
po::options_description desc("Allowed options");
desc.add_options()
("help", "produce help message")
("compression", po::value<int>(), "set compression level")
;

po::variables_map vm;
po::store(po::parse_command_line(ac, av, desc), vm);
po::notify(vm);    

if (vm.count("help")) {
     cout << desc << "\n";
     return 1;
}

if (vm.count("compression")) {
     cout << "Compression level was set to " 
          << vm["compression"].as<int>() << ".\n";
} else {
     cout << "Compression level was not set.\n";
}