import { IterableX } from './iterablex';
export declare class UnionIterable<TSource> extends IterableX<TSource> {
    private _left;
    private _right;
    private _comparer;
    constructor(left: Iterable<TSource>, right: Iterable<TSource>, comparer: (x: TSource, y: TSource) => boolean);
    [Symbol.iterator](): IterableIterator<TSource>;
}
export declare function union<TSource>(left: Iterable<TSource>, right: Iterable<TSource>, comparer?: (x: TSource, y: TSource) => boolean): IterableX<TSource>;