Util.kt

fun Int.mapToWord(): String {
  val word: String
  when (this) { // this refers to Int with its scope limited to the method level
    0 -> word = "Zero"
    1 -> word = "One"
    2 -> word = "Two"
    // 3,4,5,6,7,8,9
    else -> word = "Invalid Digit Range"
  }
  return word
}