/**
 * @description 字符串补全
 * @param value 初始值
 * @param length 返回值长度
 * @param char 用来补位的字符
 * @returns
 */
export declare function padStart(value: string | number, length: number, char?: string): string;
export declare function padEnd(value: string | number, length: number, char?: string): string;