1 package com.example 2 3 @RequiresOptIn 4 @Retention(AnnotationRetention.BINARY) 5 @Target(AnnotationTarget.CLASS, AnnotationTarget.FUNCTION) 6 annotation class MyOptIn 7 8 @OptIn(MyOptIn::class) mainnull9 fun main() { 10 print("hello world") 11 } 12