*rentries() {
        for (const i of this.#rindexes()) {
            if (this.#valList[i] !== undefined &&
                this.#keyList[i] !== undefined &&
                !this.#isBackgroundFetch(this.#valList[i])) {
                yield [this.#keyList[i], this.#valList[i]];
            }
        }
    }
Inverse order version of {@link LRUCache.entries}

Return a generator yielding `[key, value]` pairs,
in order from least recently used to most recently used.