 
 var str = "Hello, playground, let's code a Mortgage simulator app"
 
-//MARK: Helpers
+//MARK: - Helpers
 
 //: We add a method on Int to easily display from a number of months, the number of year & months it represents.
 extension Int {

    }
}

infix operator ^^ { }
func ^^ (radix: Float, power: Int) -> Float {
    return Float(pow(Double(radix), Double(power)))
}

//MARK: Models

struct MortgagePayment {
    let principal: Float


    func requiredMonthlyPayment() -> Float {
        //    M = P[i(1+i)^n]/[(1+i)^n -1]
        return (amount * ((monthlyInterestRate * (1 + monthlyInterestRate)^^months) / ((1 + monthlyInterestRate)^^months - 1)))
    }

    func theoricalTotalInterestPaid() -> Float {
