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export default class NumArray {    #presum: number[];    constructor(nums: number[]) {        const presum: number[] = Array(nums.length + 1).fill(0);        nums.forEach((value, index) => {            presum[index + 1] = value + (presum[index]);        });        this.#presum = presum;    }
    sumRange(left: number, right: number): number {        return (this.#presum[right + 1]) - this.#presum[left];    }}