/**
 * Immutably inserts the item(s) at the specified index
 *
 * @since v0.0.1
 * @category Array
 * @template {T} - The type of the array
 * @param {T[]} array - The original array
 * @param {number} index - The index of the array to start the insert; use negative value to index from the end of the array
 * @param {T[]} items - The item(s) to insert
 * @returns {T[]}
 * @example
 * insert([0, 1, 2], 1, [25])     //=> [0, 25, 1, 2]
 * insert([0, 1, 2], 1, [25, 26]) //=> [0, 25, 26, 1, 2]
 * insert([0, 1, 2], -2, [25])    //=> [0, 1, 25, 2]
 * insert([0, 1, 2], -5, [25])    //=> [25, undefined, 0, 1, 2]
 */
export declare const insertAt: <T = unknown>(array: T[], index: number, items: T[]) => T[];