/**
 * Flattens `array` a single level deep.
 *
 * @param {Array} arr The array to flatten.
 * @return {Array} Returns the new flattened array.
 * @example
 *
 * flatten([1, [2, [3, [4]], 5]]);  // => [1, 2, [3, [4]], 5]
 */
declare const flatten: <T>(arr: T[]) => T[];
export default flatten;