get(key) {
        if (!this.cache.has(key)) return undefined;
        const value = this.cache.get(key);
        this.cache.delete(key);
        this.cache.set(key, value);
        return value;
    }
Retrieves the value associated with the given key and marks the key as recently used.
@param {any} key The key to retrieve.
@returns {any} The value associated with the key, or undefined if the key does not exist.