[](Promise<R> promise, std::shared_ptr<FutureState<T>> state, F continuation) {
// ...set the new future value by running the continuation.
Future<T> future(std::move(state));
[](Promise<R> promise, std::shared_ptr<FutureState<T>> state, F continuation) {
// ...set the new future value by running the continuation.
Future<T> future(std::move(state));