Coroutines

Kotlin's coroutines have dabbled with basic support for actors, so I'm just wondering if you've got any thoughts in that direction. On Swift 5.5, they also have introduced actors which is interesting to handle data races and the other complex actors. Another thing is that one of the challenges is with testing. That's a big challenge with coroutines and having more utilities. But let me ask you this: Do you really need tests?