// in more detail.
type rangeType struct {
	typ  event.Type // "Begin" event.
	desc stringID   // Optional subtype.
}

// makeRangeType constructs a new rangeType.
func makeRangeType(typ event.Type, desc stringID) rangeType {
	if styp := go122.Specs()[typ].StartEv; styp != go122.EvNone {
		typ = styp
	}
	return rangeType{typ, desc}
}