oops with swift

class Maths {//1    //2    let a: Int!    let b: Int!    private var result: Int?    //3    init(a: Int,b: Int) {        self.a = a        self.b = b    }    //4    func add() {        result = a + b    }    //5    func displayResult() {        print("Result - \(result)")    }}let calculation = Maths(a: 2, b: 3)calculation.add()calculation.displayResult()