Add and implement an extension function 'isEmptyOrNull()' on the type String?. It should return true, if the string is null or empty

fun main(args: Array<String>) {

    val s1: String? = null

    val s2: String? = ""

    s1.isEmptyOrNull() == true

    s2.isEmptyOrNull() == true

​

    val s3 = "   "

    s3.isEmptyOrNull() == false

}

​

infix fun <T> T.isEqualTo(other: T) {

    if (this == other) println("OK")

    else println("Error: $this != $other")

}

​

fun String?.isEmptyOrNull() = this == null || isEmpty()