스레드를 만드는 함수의 인자로 넘겨주는 함수의 리턴 값을 받아오고 싶은 경우 어떻게 해야하나요?

#include <iostream>
#include <future>
#include <chrono>
using namespace std;
 
static int DeepThought(void);
 
int main(void) {
	future<int> fut_ans = async(launch::async, DeepThought);
 
	cout << "Calculating the Answer to the Ultimate Question of Life, the Universe, and Everything" << flush;
	while (fut_ans.wait_for(chrono::seconds(1)) == future_status::timeout)
		cout << '.' << flush;
 
	int ans = fut_ans.get();
	cout << endl << "The answer is " << ans << '.' << endl;
 
	return 0;
}
 
static int DeepThought(void) {
	this_thread::sleep_for(chrono::microseconds(7500000));	// We cannot wait for 7.5 million years.
	return 42;
}