Kotlin - Generics

class Box<T> {
    private var element: T? = null

    fun put(e: T) {
        element = e
    }

    fun get(): T? = element
}

fun main(args: Array<String>) {
    val bString = Box<String>()
    bString.put("opa")

    val bInt = Box<Int>()
    bInt.put(10)

    println(bString.get()?.length)
    println(bInt.get()?.plus(1))
}