/**
 * Lighten / Darkens a hex color code. Only works for 6 character hex codes!
 * @private
 * @param color - hex color code to apply the function to
 * @param percent - positive/negative value between [-1,1] to lighten/darken color
 * @returns lightened/darkened hex code of the input color
 */
export declare function lighten(color: string, percent: number): string;