message: specify associated type
diff: @@ -176,7 +176,7 @@ impl<T: 'static + Send> Responder<T> {
  impl<T> Responder<T> {
  /// Send `data` to the origin of the request.
  - pub(crate) fn respond(mut self, data: T) -> impl Future {
  + pub(crate) fn respond(mut self, data: T) -> impl Future<Output = ()> {
  let caller_backtrace = backtrace::Backtrace::new();
  async move {
  if let Some(sender) = self.0.take() {
  