code: func (e ExperimentalMiddleware) WrapHandler(handler func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error) func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
  	return func(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
  		w.Header().Set("Docker-Experimental", e.experimental)
  		return handler(ctx, w, r, vars)
  	}
  }
docs: // WrapHandler returns a new handler function wrapping the previous one in the request chain.