import { PipelineOperator } from "../../core";
/**
 * Randomly selects the specified number of documents from its input.
 *
 * See {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation/sample/ usage}.
 *
 * @param collection
 * @param expr
 * @param _options
 * @returns
 */
export declare const $sample: PipelineOperator;