可配置的乘數作為 curried 函式
def multiply(factor: Int)(numberToBeMultiplied: Int): Int = factor * numberToBeMultiplied
val multiplyBy3 = multiply(3)_ // resulting function signature Int => Int
val multiplyBy10 = multiply(10)_ // resulting function signature Int => Int
val sixFromCurriedCall = multiplyBy3(2) //6
val sixFromFullCall = multiply(3)(2) //6
val fortyFromCurriedCall = multiplyBy10(4) //40
val fortyFromFullCall = multiply(10)(4) //40