/**
 * Returns the element at a specified index in a sequence or undefined if the index is out of range.
 *
 * @export
 * @template T The type of the elements in the source sequence.
 * @param {Iterable<T>} source iterable sequence to return the element from.
 * @param {number} index The zero-based index of the element to retrieve.
 * @returns {(T | undefined)} An iterable sequence that produces the element at the specified
 * position in the source sequence, or undefined if the index is outside the bounds of the source sequence.
 */
export declare function elementAt<T>(source: Iterable<T>, index: number): T | undefined;