How to use the hazelcast-client.Aggregators function in hazelcast-client

*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

var Client = require('hazelcast-client').Client;
var Aggregators = require('hazelcast-client').Aggregators;
var Predicates = require('hazelcast-client').Predicates;

Client.newHazelcastClient().then(function (hazelcastClient) {
    var client = hazelcastClient;
    var map;
    hazelcastClient.getMap('person-age-map').then(function (mp) {
        map = mp;
        return map.putAll([
            ['Philip', 46],
            ['Elizabeth', 44],
            ['Henry', 13],
            ['Paige', 15]
        ])
    }).then(function () {
        return map.aggregate(Aggregators.count());
    }).then(function (count) {