public static ILoggingBuilder AddSubscription(this ILoggingBuilder builder, IObserver <SubscriberLogEntry> subscriber)
        {
            SubscriptionLogProvider prov = new SubscriptionLogProvider();

            prov.Subscribe(subscriber);
            return(builder.AddProvider(prov));
        }
        public static ILoggerFactory AddSubscription(this ILoggerFactory factory, IObserver <SubscriberLogEntry> subscriber)
        {
            SubscriptionLogProvider prov = new SubscriptionLogProvider();

            prov.Subscribe(subscriber);
            factory.AddProvider(prov);
            return(factory);
        }