import { Options } from '../../core';
import { Iterator } from '../../lazy';
/**
 * Categorizes incoming documents into a specific number of groups, called buckets,
 * based on a specified expression. Bucket boundaries are automatically determined
 * in an attempt to evenly distribute the documents into the specified number of buckets.
 * https://docs.mongodb.com/manual/reference/operator/aggregation/bucketAuto/
 *
 * @param {*} collection
 * @param {*} expr
 * @param {*} options
 */
export declare function $bucketAuto(collection: Iterator, expr: any, options: Options): Iterator;