#include <iostream>
#include <utility>
#include <string_view>

// Simple parser that returns {true,42} for the literal "42",
// otherwise returns {false,0}.
std::pair<bool,int> try_parse(std::string_view s) {
    if (s == "42") return {true, 42};
    return {false, 0};
}

int main() {
    std::string_view input = "42";
    if (auto [ok, n] = try_parse(input); ok) {
        std::cout << "got " << n << '\n';
    }
    return 0;
}