/**
 * <zh/> 数组去重
 *
 * <en/> deduplicate array
 * @param arr - <zh/> 数组 | <en/> array
 * @param by - <zh/> 通过某个属性去重 | <en/> deduplicate by some property
 * @returns <zh/> 去重后的数组 | <en/> deduplicated array
 */
export declare function deduplicate<T>(arr: T[], by?: (item: T) => unknown): T[];