How to use the ibm-watson/natural-language-understanding/v1.js function in ibm-watson

'use strict';

var fs = require('fs');
var NaturalLanguageUnderstandingV1 = require('ibm-watson/natural-language-understanding/v1.js');
require('dotenv').config({ silent: true }); //  optional

var nlu = new NaturalLanguageUnderstandingV1({
  // note: if unspecified here, credentials are pulled from environment properties:
  // NATURAL_LANGUAGE_UNDERSTANDING_USERNAME &  NATURAL_LANGUAGE_UNDERSTANDING_PASSWORD
  // username: ''.
  // password: '',
  version: '2018-04-05',
  url: 'https://gateway.watsonplatform.net/natural-language-understanding/api/'
});

var filename = '../test/resources/natural_language_understanding/energy-policy.html';
fs.readFile(filename, 'utf-8', function(file_error, file_data) {
  if (file_error) {
    console.log(file_error);
  } else {
    var options = {
      html: file_data,
      features: {

*      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.
 */

const express = require('express');
const NaturalLanguageUnderstandingV1 = require('ibm-watson/natural-language-understanding/v1.js');
const { IamAuthenticator } = require('ibm-watson/auth');

const app = express();
// Create the service wrapper
const nlu = new NaturalLanguageUnderstandingV1({
  version: '2018-04-05',
  authenticator: new IamAuthenticator({
    apikey: process.env.NATURAL_LANGUAGE_UNDERSTANDING_IAM_APIKEY || 'type-key-here',
  }),
  url: process.env.NATURAL_LANGUAGE_UNDERSTANDING_URL,
});

// setup body-parser
const bodyParser = require('body-parser');

app.use(bodyParser.json());

// Bootstrap application settings
require('./config/express')(app);

app.get('/', (req, res) => {

silent: true
});

const express = require('express'); // app server
const bodyParser = require('body-parser'); // parser for post requests
const numeral = require('numeral');
const fs = require('fs'); // file system for loading JSON

const AssistantV1 = require('ibm-watson/assistant/v1');
const DiscoveryV1 = require('ibm-watson/discovery/v1');
const NaturalLanguageUnderstandingV1 = require('ibm-watson/natural-language-understanding/v1.js');
const ToneAnalyzerV3 = require('ibm-watson/tone-analyzer/v3');

const assistant = new AssistantV1({ version: '2019-06-17' });
const discovery = new DiscoveryV1({ version: '2019-04-17' }); // PRE-SDU VERSION!
const nlu = new NaturalLanguageUnderstandingV1({ version: '2019-06-17' });
const toneAnalyzer = new ToneAnalyzerV3({ version: '2019-06-17' });

const bankingServicesIN = require('./banking_services');
const bankingServicesUS = require('./banking_services_us');
const WatsonDiscoverySetup = require('./lib/watson-discovery-setup');
const WatsonAssistantSetup = require('./lib/watson-assistant-setup');

const DEFAULT_NAME = 'watson-banking-chatbot';
const DISCOVERY_ACTION = 'rnr'; // Replaced RnR w/ Discovery but Assistant action is still 'rnr'.
const locale = process.env.LOCALE;
let DISCOVERY_DOCS = [
  './data/discovery/docs/BankFaqRnR-DB-Failure-General.docx',
  './data/discovery/docs/BankFaqRnR-DB-Terms-General.docx',
  './data/discovery/docs/BankFaqRnR-e2eAO-Terms.docx',
  './data/discovery/docs/BankFaqRnR-e2ePL-Terms.docx',
  './data/discovery/docs/BankRnR-OMP-General.docx'

private init(): any {
        return new nlup({
            version: '2019-07-12',
            iam_apikey: this._apikey,
            url: this._url
        });
    }
    private async recognize(text: string, type: string): Promise {