fun f(x: Any): String {
  when {
    x is A<*> -> { // BLOCK
      return x /*as A<*> */.call(block = local fun <anonymous>(y: Any?): @FlexibleNullability String? {
        return "OK"
      }
 /*-> I<out @FlexibleNullability Any?> */) /*!! String */
    }
  }
  return "Fail"
}