/** Subset of the elemental2 Promise API. */
@JsType(isNative = true, namespace = JsPackage.GLOBAL, name = "Promise")
class Promise<T extends @Nullable Object> implements IThenable<T> {

  @JsFunction
  interface PromiseExecutorCallbackFn<T extends @Nullable Object> {
    @JsFunction
    interface ResolveCallbackFn<T extends @Nullable Object> {
      void onInvoke(T value);
    }

    @JsFunction
    interface RejectCallbackFn {