/**
 * For a provided hex color, returns an inverted color for legibility.
 * @param  {[type]} hex - hexadecimal (HTML) color, e.g. #FFFFFF
 * @param  {[type]} bw  - whether to return only black or white as inverted color
 * @return {[type]}     [description]
 */
export function invertColor(hex: [any], bw?: [any]): [any];
export function padZero(str: any, len: any): string;