Trailing lambda's in Kotlin

In Kotlin, you can do things like:

class Hello {
    val secretValue = 1;
    fun trailingLambda(trail: Hello.() -> Unit = {}) { trail() }
}

fun main() {
  val hallo: Hello = Hello()
  hallo.trailingLambda { println("trailingLambda ${this.secretValue}") }
}

Read more here.