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export default class MovingAverage {    #queue: number[];    #size: number;    #sum: number;    constructor(size: number) {        if (size < 1) throw Error("size invalid");        this.#queue = [];        this.#size = size;        this.#sum = 0;    }
    next(val: number): number {        this.#queue.push(val);        this.#sum += val;
        while (this.#queue.length > this.#size) {            const first = this.#queue.shift();            if (first) {                this.#sum -= first;            }        }
        return this.#sum / this.#queue.length;    }}