Okay, I'm dumb, but I can't figure out how to use the *instances()

Uh, I'm showing my js noobery here, but for the life of me, I don't understand this entry in the manual:

*pickedInstances()

Iterates over the instances that have been picked by the event's conditions. This is only useful with scripts in event sheets.

How do I use it?

For general instances I would do something like this:

const enemies = runtime.objects.enemies.getAllInstances()

enemies.foreach((i) => {

	Utils.DoSomething(i, 60*runtime.dt);

});

//or

for(let i = enemies.length(); i>= 0; --i) {
	Utils.DoSomething("42");
}

you can use iterators like this

for (const inst of runtime.objects.Sprite.instances()) {	
}

Thanks, much appreciated!