#include <coroutine>#include <iostream>#include <utility> template<class T>struct task{struct promise_type{auto get_return_object(){return task(std::coroutine_handle<promise_type>::from_promise(*this));}std::suspend_always initial_suspend(){return{};}struct final_awaiter{bool await_ready()noexcept{returnfalse;}void await_resume()noexcept{}std::coroutine_handle<>                await_suspend(std::coroutine_handle<promise_type> h)noexcept{// final_awaiter::await_suspend is called when the execution of the// current coroutine (referred to by 'h') is about to finish.// If the current coroutine was resumed by another coroutine via// co_await get_task(), a handle to that coroutine has been stored// as h.promise().previous. In that case, return the handle to resume// the previous coroutine.// Otherwise, return noop_coroutine(), whose resumption does nothing. if(auto previous= h.promise().previous; previous)return previous;elsereturn std::noop_coroutine();}};        final_awaiter final_suspend()noexcept{return{};}void unhandled_exception(){throw;}void return_value(T value){ result= std::move(value);}         T result;std::coroutine_handle<> previous;};     task(std::coroutine_handle<promise_type> h): coro(h){}    task(task&& t)= delete;    ~task(){ coro.destroy();} struct awaiter{bool await_ready(){returnfalse;}        T await_resume(){return std::move(coro.promise().result);}auto await_suspend(std::coroutine_handle<> h){            coro.promise().previous= h;return coro;}std::coroutine_handle<promise_type> coro;};    awaiter operator co_await(){return awaiter{coro};}    T operator()(){        coro.resume();return std::move(coro.promise().result);} private:std::coroutine_handle<promise_type> coro;}; task<int> get_random(){std::cout<<"in get_random()\n";    co_return4;} task<int> test(){    task<int> v= get_random();    task<int> u= get_random();std::cout<<"in test()\n";int x=(co_await v+ co_await u);    co_return x;} int main(){    task<int> t= test();int result= t();std::cout<< result<<'\n';}

in test()in get_random()in get_random()8