/**
 * @function sum
 * @desc 求参数之和
 * @see sumArray
 * @param {number[]} arr
 * @returns {number} 和
 * @example Mathx.sumArray(1, 2, 3); // 6;
 * Mathx.sumArray(1, 2, 3, 4, 5); // 15;
 */
export declare const sum: (...arr: number[]) => number;