/**
 * Removes all occurrences of needle from the end of haystack.
 *
 * @param haystack string to trim
 * @param needle the thing to trim
 *
 * @example
 *
 *      rtrim('Helloabcabc', 'abc'); //=> 'Hello'
 *      rtrim('  Hello  ');          //=> '  Hello'
 *
 */
export declare function rtrim(haystack: string, needle?: string): string;