import { AccumulatorOperator, AnyObject } from "../../types";
/**
 * Combines multiple documents into a single document.
 *
 * @param {Array} collection The input array
 * @param {AnyObject} _ The right-hand side expression value of the operator
 * @param {Options} options The options to use for this operation
 * @returns {Array|*}
 */
export declare const $mergeObjects: AccumulatorOperator<AnyObject>;