Suppose I have the following code :

fun main() {
    val userName: String? = "Dmitry" // line 1
    userName?.takeLast(2)?.reversed() // line 2
    userName?.plus("kotlin").plus("lang") // line 3
}

I can’t get the reason for the usage of Elvis operator before reversed() – why it is not possible to use just . ? As I can see in doc takeLast() always provides String, not String?. The same scenario works for Line 3 in my example -> plus() always returns String so there is no need of Elvis before the Second plus() ?