code: func NewSubscriberWrapper(ot opentracing.Tracer) server.SubscriberWrapper {
  	return func(next server.SubscriberFunc) server.SubscriberFunc {
  		return func(ctx context.Context, msg server.Message) error {
  			name := "Pub to " + msg.Topic()
  			if ot == nil {
  				ot = opentracing.GlobalTracer()
  			}
  			ctx, span, err := StartSpanFromContext(ctx, ot, name)
  			if err != nil {
  				return err
  			}
  			defer span.Finish()
  			return next(ctx, msg)
  		}
  	}
  }
docs: // NewSubscriberWrapper accepts an opentracing Tracer and returns a Subscriber Wrapper