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