func ServerShutdownSignalFrom(ctx context.Context) ServerShutdownSignal {
	ev, _ := ctx.Value(serverShutdownSignalKey).(ServerShutdownSignal)
	return ev
}

// WithServerShutdownSignal returns a new context that stores
// the ServerShutdownSignal interface instance.
func WithServerShutdownSignal(parent context.Context, window ServerShutdownSignal) context.Context {
	if ServerShutdownSignalFrom(parent) != nil {
		return parent // Avoid double registering.
	}

			return
		}

		// attach ServerShutdownSignal to the watch request so that the
		// watch handler loop can return as soon as the server signals
		// that it is shutting down.
		ctx = apirequest.WithServerShutdownSignal(req.Context(), termination)
		req = req.WithContext(ctx)

		defer wg.Done()
		handler.ServeHTTP(w, req)
	})