import { PipelineOperator } from "../../core";
/**
 * Writes the resulting documents of the aggregation pipeline to a collection.
 *
 * NB: Object are deep cloned for outputing regardless of the ProcessingMode.
 *
 * See {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation/merge/ usage}.
 *
 * @param collection
 * @param expr
 * @param options
 * @returns
 */
export declare const $merge: PipelineOperator;