import { PipelineOperator } from "../../core";
/**
 * Returns a count of the number of documents at this stage of the aggregation pipeline.
 *
 * See {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation/count usage}.
 *
 * @param collection
 * @param expr
 * @param _options
 * @returns
 */
export declare const $count: PipelineOperator;