[zozbot234]

Coroutines/resumable functions are not restricted to yielding to a single runtime or event loop, they can simply "resume" each other directly. There are also extensions of coroutines that are more than one-shot (a resumable function where the current state can be copied and invoked more than once) and/or are allowed to provide values when "resuming" other code, which also goes beyond the common "event loop" model.