The Any type

All types in Kotlin extend from the Any type (hold on a second, actually this isn't true but for the sake of the explanation, bear with me).

Every class and interface that we create implicitly extends Any. So, if we write a method that takes Any as a parameter, it will receive any value:

fun main(args: Array<String>) {
    
    val myAlmondCupcake = Cupcake.almond()
    
    val anyMachine = object : Machine<Any> {
      override fun process(product: Any) {
        println(product.toString())
      }
    }
    
    anyMachine.process(3)
    
    anyMachine.process("")
    
    anyMachine.process(myAlmondCupcake)    
}

What about a nullable value? Let's have a look at it:

fun main(args: Array<String>) {
    
    val anyMachine = object : Machine<Any> {
      override fun process(product: Any) {
        println(product.toString())
      }
    }

    val nullableCupcake: Cupcake? = Cupcake.almond()

    anyMachine.process(nullableCupcake) //Error:(32, 24) Kotlin: Type mismatch: inferred type is Cupcake? but Any was expected
}

Any is the same as any other type and also has a nullable counterpart, Any?.  Any extends from Any?. So, in the end, Any? is the top class of Kotlin's type system hierarchy.