import { Iterator } from "../../lazy";
import { Options } from "../../types";
/**
 * Randomly selects the specified number of documents from its input.
 *
 * See {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation/sample/ usage}.
 */
export declare function $sample(coll: Iterator, expr: {
    size: number;
}, _options: Options): Iterator;