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export default class Twitter {    #time = 0;    #follower_to_followees: Map<number, Set<number>> = new Map();
    #user_to_tweets: Map<number, Set<number>> = new Map();    #tweet_to_time = new Map<number, number>();    constructor() {}    #deleteTweet(userId: number, tweetId: number): void {        const tweets = this.#user_to_tweets.get(userId);        if (tweets) {            tweets.delete(tweetId);        }
        this.#tweet_to_time.delete(tweetId);    }    postTweet(userId: number, tweetId: number): void {        const time = this.#time;        this.#tweet_to_time.set(tweetId, time);        const tweets = this.#user_to_tweets.get(userId) ?? new Set();        tweets.add(tweetId);        this.#user_to_tweets.set(userId, tweets);        this.#time++;
        if (tweets.size > 10) {            const oldestTweet = tweets.values().next().value;            this.#deleteTweet(userId, oldestTweet);        }    }
    getNewsFeed(userId: number): number[] {        const followees = this.#follower_to_followees.get(userId);        const tweets = Array.from(this.#user_to_tweets.get(userId) ?? []);        if (followees) {            for (const followee of followees) {                const userTweets = this.#user_to_tweets.get(followee);                if (userTweets) {                    userTweets.forEach((tweet) => tweets.push(tweet));                }            }        }
        const sortedTweets = tweets            .sort((a, b) => {                const timeA = this.#tweet_to_time.get(a) ?? 0;                const timeB = this.#tweet_to_time.get(b) ?? 0;                return timeB - timeA;            })            .slice(0, 10);
        return sortedTweets;    }
    follow(followerId: number, followeeId: number): void {        const followee = this.#follower_to_followees.get(followerId) ??            new Set();
        followee.add(followeeId);        this.#follower_to_followees.set(followerId, followee);    }
    unfollow(followerId: number, followeeId: number): void {        this.#follower_to_followees.get(followerId)?.delete(followeeId);    }}