func PublisherContext(ctx context.Context) Publisher {
	pub, ok := ctx.Value(KeyPublisher).(Publisher)
	if !ok {
		return nil
	}

	return pub
}
func PublisherContext(ctx context.Context) Publisher {
	pub, ok := ctx.Value(KeyPublisher).(Publisher)
	if !ok {
		return nil
	}

	return pub
}
// PublisherContext return the publisher.