/**
 * @example
 * // 17 = 10001(2)
 * getBitValue(17, 0)
 * // 1
 * @example
 * getBitValue(17, 1)
 * // 0
 * @example
 * getBitValue(17, 4)
 * // 1
 * @param {Number} idx, idx is reverse, and it begins 0
 * @returns {Number} a num
 */
export declare const getBitValue: (num: number, idx: number) => number;