filters.go
func Items(items ...string) Filter {
	return FilterFunc(func(arg Arg) error {
		for _, s := range items {
			arg.Out <- s
		}
		return nil
	})
}
func Items(items ...string) Filter {
	return FilterFunc(func(arg Arg) error {
		for _, s := range items {
			arg.Out <- s
		}
		return nil
	})
}
// Items emits items.