import { Stream } from '../index';
/**
 * Group consecutive pairs of events as arrays. Each array has two items.
 *
 * Marble diagram:
 *
 * ```text
 * ---1---2-----3-----4-----5--------|
 *       pairwise
 * -------[1,2]-[2,3]-[3,4]-[4,5]----|
 * ```
 *
 * Example:
 *
 * ```js
 * import pairwise from 'xstream/extra/pairwise'
 *
 * const stream = xs.of(1, 2, 3, 4, 5, 6).compose(pairwise)
 *
 * stream.addListener({
 *   next: i => console.log(i),
 *   error: err => console.error(err),
 *   complete: () => console.log('completed')
 * })
 * ```
 *
 * ```text
 * > [1,2]
 * > [2,3]
 * > [3,4]
 * > [4,5]
 * > [5,6]
 * > completed
 * ```
 *
 * @return {Stream}
 */
export default function pairwise<T>(ins: Stream<T>): Stream<[T, T]>;