suspend fun yield(): Unit (source)

Yields a thread (or thread pool) of the current coroutine dispatcher to other coroutines to run. If the coroutine dispatcher does not have its own thread pool (like Dispatchers.Unconfined) then this function does nothing, but checks if the coroutine Job was completed. This suspending function is cancellable. If the Job of the current coroutine is cancelled or completed when this suspending function is invoked or while this function is waiting for dispatching, it resumes with CancellationException.