/**
 * Maps over items sequentially, awaiting each async function before the next
 * @param {T[]} items The items to process
 * @param {(item: T, index: number) => Promise<U>} function_ The async mapper
 * @returns {Promise<U[]>} Results in the same order as the input items
 * @example
 * const results = await mapSeries([1, 2, 3], async (n) => n * 2);
 * // [2, 4, 6]
 */
export declare const mapSeries: <T, U>(items: T[], function_: (item: T, index: number) => Promise<U>) => Promise<U[]>;