/**
 * Returns a unique string. If template is supplied and contains a replaceable string (see node library util.format)
 * the unique string will be applied to the template using util.format. If the template does not contain a replaceable
 * string the unique string will be appended to the template.
 *
 * @param {string} template - can contain a replaceable string (%s)
 * @returns {string}
 */
export declare const genUniqueString: (template?: string) => string;