Stack vs Heap memory management

FunFact.kt

fun main() {
  val actor = Actor("Will", "Smith", 53) // (1)
  val forName = actor.forName // (2)
  val funFact = actor.getFunFact(forName) // (3)
  println(funFact)
}
 
class Actor(val forName: String, val name: String, val age: Int) {
  
  fun getFunFact(key: String?): String? = funFacts[key] // (3')
}

private val funFacts = mutableMapOf(
  "Will" to "slapped Chris Rock in the face at the Academy Awards"
)