message: Added a `#[must_use]` to Responder
diff: @@ -115,6 +115,7 @@ pub type Effects<Ev> = Multiple<Effect<Ev>>;
  type Multiple<T> = SmallVec<[T; 2]>;
  /// A responder satisfying a request.
  +#[must_use]
  pub struct Responder<T>(oneshot::Sender<T>);
  impl<T: 'static + Send> Responder<T> {
  