import { IterableX } from '../iterable';
/**
 * Expands the sequence by recursively applying a selector function.
 * @param {Iterable<T>} source Source sequence.
 * @param {function(value: T): Iterable<T>} selector Selector function to retrieve the next sequence to expand
 * @return {Iterable<T>} Sequence with results from the recursive expansion of the source sequence.
 */
export declare function expand<TSource>(source: Iterable<TSource>, selector: (value: TSource) => Iterable<TSource>): IterableX<TSource>;