my first lambda use in c++

lambda-calculator.cpp

#include "pch.h" // for visual studio usage
#include <iostream>
#include <functional>

class Calculator {
public:
	Calculator(int num) : _baseNum(num) {};

	int add(int a, int b) {

		auto addTwoIntegers = [](int x) -> std::function<int(int)> {
			return [=](int y) {
				return x + y;
			};
		};

		auto higherOrder = [this](const std::function<int(int)>& fn, int z) {
			return _baseNum + fn(z);
		};

		return higherOrder(addTwoIntegers(a), b);

	}
private:
	int _baseNum;
};

int main()
{
	Calculator cal(10);
	std::cout << "Answer: " << cal.add(5, 5) << std::endl;
}