Function adopted from https://stackoverflow.com/questions/20833453/comparing-stdfunctions-for-equality

* Attempts to fufill the promise with a value. This will trigger the functions * registered with OnSuccess if successful. * * @return True if

* Indicates whether the promise has been fufilled. * * @return true if this promise has been fufilled; false otherwise. */

* Attempts to invalidate the promise, indicating that no value ever be * returned. This will trigger the functions registered with OnFailure if *