/**
 * Increases the opacity of a color. Its range for the amount is between 0 to 1.
 *
 * @example
 * background: opacify(0.1, 'rgba(255, 255, 255, 0.9)');
 * background: opacify(0.2, 'hsla(0, 0%, 100%, 0.5)'),
 * background: opacify(0.5, 'rgba(255, 0, 0, 0.2)'),
 */
export declare function opacify(amount: number, color: string): string;