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export default ((guess: (num: number) => number) =>    function guessNumber(n: number): number {        let left = 1;        let right = n;        while (left < right) {            const mid = Math.floor((left + right) / 2);            const diff = guess(mid);            if (diff === 0) return mid;            if (diff > 0) {                left = mid + 1;            }            if (diff < 0) {                right = mid;            }        }        return left;    });