Rewrite functional iterators into for loop statement

[kirugan]

In go 1.23 they accepted functional iterators. We haven't used for loop statement because it wasn't clear what final interface would look like.
One can find all functional iterators by searching usages of iter.Seq or iter.Seq2 types.
Example:

eventsIt(func(res *spec.EventsResponse) bool {
	switch v := res.EventMessage.(type) {
	case *spec.EventsResponse_Event:
		events = append(events, v.Event)
		return true
	case *spec.EventsResponse_Fin:
		return false
	default:
		s.log.Warnw("Unexpected EventMessage from getEvents", "v", v)
		return false
	}
})

to be:

loop:
for res := range eventsIt {
	switch v := res.EventMessage.(type) {
	case *spec.EventsResponse_Event:
		events = append(events, v.Event)
	case *spec.EventsResponse_Fin:
                break loop // mind the loop label, because just break key word doesn't affect iteration
	default:
		s.log.Warnw("Unexpected EventMessage from getEvents", "v", v)
		break loop
	}
})

or

for res := range eventsIt {
	switch v := res.EventMessage.(type) {
	case *spec.EventsResponse_Event:
		events = append(events, v.Event)
                continue // as far as I remember continue works fine inside select
	case *spec.EventsResponse_Fin:
                // will break in the end
	default:
		s.log.Warnw("Unexpected EventMessage from getEvents", "v", v)
	}
        // comment why
	break
})

P.S. First you need to add GOEXPERIMENT=rangefunc env var. I suggest to put it on top of Makefile

[AnkushinDaniil]

Added env var

[obasekiosa]

@kirugan
anyone working on this?