1-Vehicle.kt

interface Vehicle {
    fun drive()
}

class Bike(val speed: Double): Vehicle {
    override fun drive() = println("Driving Bike at $speed KMPH")
}

class Car(val speed: Double): Vehicle {
    override fun drive() = println("Driving Car at $speed KMPH")
}

2-Main.kt

class SportsBike(v: Vehicle): Vehicle by v
class SportsCar(v: Vehicle): Vehicle by v

fun main() {
    val bike = Bike(50.0)
    SportsBike(bike).drive() // prints "Driving Bike at 50.0 KMPH"
    
    val car = Car(100.0)
    SportsCar(car).drive() // prints "Driving Car at 100.0 KMPH"
}