code: func (rww *responseWriterWrapper) CloseNotify() <-chan bool {
  	if cn, ok := rww.w.(http.CloseNotifier); ok {
  		return cn.CloseNotify()
  	}
  	panic(httpserver.NonCloseNotifierError{Underlying: rww.w})
  }
docs: // CloseNotify implements http.CloseNotifier.
  // It just inherits the underlying ResponseWriter's CloseNotify method.
  // It panics if the underlying ResponseWriter is not a CloseNotifier.