public function async_update( array $to_update, $return_promise = true ) {
		$promise = new Tribe__Promise( $this->get_update_callback( $to_update, true ), $to_update );
		if ( ! $return_promise ) {
			// Dispatch it immediately and return the IDs that will be deleted.
			$promise->save()->dispatch();

			return $to_update;
		}

		// Return the promise and let the client do the dispatching.
		return $promise;
	}