/**
 * Maps an item in an array at a specified index to a new value.
 * @param array The array to map the item in.
 * @param index The index of the item to map.
 * @param mapFn A function that maps the item to a new value.
 * @returns A new array with the mapped item.
 * @example
 * const originalArray = [1, 2, 3, 4, 5]
 * const mappedArray = mapAt(originalArray, 2, (item) => item * 2)
 * // Returns [1, 2, 6, 4, 5]
 */
export declare const mapAt: <T>(array: T[], index: number, mapFn: (item: T) => T) => T[];