import { Iterator } from "../../lazy";
import { AnyObject, Options } from "../../types";
/**
 * Reshapes each document in the stream, such as by adding new fields or removing existing fields.
 * For each input document, outputs one document.
 *
 * See {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation/project usage}.
 */
export declare function $project(coll: Iterator, expr: AnyObject, options: Options): Iterator;