How to use the browserstack.local function in browserstack

this.Before(function (scenario, callback) {
    world = this;
    var task_id = parseInt(process.env.TASK_ID || 0);
    var caps = config.capabilities[task_id];
    caps['browserstack.user'] = username;
    caps['browserstack.key'] = accessKey;

    // Make the broswer name available to scripts (easily)
    globals.browser_name = caps['browserName'];

    if(caps["browserstack.local"]){
      // Code to start browserstack local before start of test and stop browserstack local after end of test
      bs_local = new browserstack.Local();
      bs_local.start({'key': accessKey }, function(error) {
        if (error) return console.log(error.red);

        world.driver = createBrowserStackSession(config, caps);
        callback();
      });
    }
    else {
      world.driver = createBrowserStackSession(config, caps);
      callback();
    }
  });

import {Capability, Browser} from 'selenium-webdriver';

const capabilities = {
  [Capability.PLATFORM]: 'WINDOWS',
  [Capability.BROWSER_NAME]: Browser.CHROME,
  [Capability.VERSION]: 73,
};

// browserstack specific capabilities - https://www.browserstack.com/automate/capabilities
if (process.env.CI) {
  capabilities['browserstack.local'] = true;
  capabilities['browserstack.localIdentifier'] = process.env.BROWSERSTACK_LOCAL_IDENTIFIER || process.env.TRAVIS_JOB_NUMBER;
  capabilities['browserstack.networkLogs'] = true;
  capabilities.os = 'WINDOWS';
  capabilities.os_version = '10';
  capabilities.browser = Browser.CHROME;
  capabilities.browser_version = '73';
}

export default capabilities;

this.Before(function (scenario, callback) {
    var world = this;
    var task_id = parseInt(process.env.TASK_ID || 0);
    var caps = config.capabilities[task_id];
    caps['browserstack.user'] = username;
    caps['browserstack.key'] = accessKey;

    if(caps["browserstack.local"]){
      // Code to start browserstack local before start of test and stop browserstack local after end of test
      bs_local = new browserstack.Local();
      bs_local.start({'key': accessKey }, function(error) {
        if (error) return console.log(error.red);

        world.driver = createBrowserStackSession(config, caps);
        callback();
      });
    }
    else {
      world.driver = createBrowserStackSession(config, caps);
      callback();
    }
  });

function createCapabilities (capabilities, tags) {

    capabilities['browserstack.user']             = env.BROWSERSTACK_USER || env.BS_USERNAME;
    capabilities['browserstack.key']              = env.BROWSERSTACK_KEY || env.BS_AUTHKEY;
    capabilities['browserstack.local']            = true;

    // Selenium 3.4.0 does not work great with IE11
    if (capabilities.browserName !== 'internet explorer') {
        capabilities['browserstack.selenium_version'] = '3.4.0';
    }

    capabilities.project = pkg.name;
    capabilities.build   = env.BROWSERSTACK_BUILD || pkg.version;

    capabilities.cucumberOpts = {
        format: 'json:./test/reports/' + composeReportName(capabilities) + '.json'
    };

    if (tags) {
        capabilities.cucumberOpts.tags = tags;
    }

const { argv } = require('yargs');
const { browserConf } = require('./browser-config');
const { constants } = require('../constants');

const wdioMaster = require('./wdio.conf.js');
const selectedBrowser = argv.browser
  ? browserConf[argv.browser]
  : browserConf['chrome'];
// Enable When browserstack support Selenium 3.13.0
// const seleniumSettings = require('./selenium-config');

const username = process.env.MANAGER_USER;
const password = process.env.MANAGER_PASS;

if (argv.local) {
  selectedBrowser['browserstack.local'] = true;
} else {
  selectedBrowser['browserstack.local'] = false;
}

// Enable When browserstack support Selenium 3.13.0
//selectedBrowser['browserstack.selenium_version'] = seleniumSettings.version;
selectedBrowser['browserstack.selenium_version'] = '3.11.0';

exports.config = merge(wdioMaster.config, {
  host: 'hub.browserstack.com',
  services: ['browserstack'],
  capabilities: [selectedBrowser],
  user: process.env.BROWSERSTACK_USERNAME,
  key: process.env.BROWSERSTACK_ACCESS_KEY,
  browserstackLocal: argv.local ? true : false,
  browserstackLocalForcedStop: true,

edge: {
      browser: 'Edge',
      browserVersion: '16.0',
    },
  },
};

// Copy seleniumhost/port into test settings
Object.values(config.test_settings).forEach((setting) => {
  setting.selenium_host = config.selenium.host;
  setting.selenium_port = config.selenium.port;
});

if (process.env.LOCAL_TEST) {
  config.test_settings.default.desiredCapabilities['browserstack.local'] = true;
}

module.exports = config;

function (capabilities) {
        capabilities['browserstack.user']  = BROWSERSTACK_USER;
        capabilities['browserstack.key']   = BROWSERSTACK_KEY;
        capabilities['browserstack.local'] = true;

        // Selenium 3.6.0 does not work great with IE11
        if (capabilities.browserName !== 'internet explorer') {
            capabilities['browserstack.selenium_version'] = '3.4.0';
        }

        capabilities.project = pkg.name;
        capabilities.build   = env.BROWSERSTACK_BUILD || pkg.version;

        if (capabilities.browserName === 'internet explorer') {
            capabilities.ignoreProtectedModeSettings = true;
        }

        return capabilities;
    }
);

export function configProtractor() {
    var browserstack = extend(true /* Deep copy. */, {}, protractorUtils.platform.browserstack);

    var protractorBaseConfig = {
        specs: __dirname + '/../../tests/e2e/*.js'
    };

    // browserstack.capabilities['browserstack.user'] = process.env.BROWSERSTACK_USER;
    browserstack.capabilities['browserstack.user'] = process.env.bs_user;
    // browserstack.capabilities['browserstack.key'] = process.env.BROWSERSTACK_KEY;
    browserstack.capabilities['browserstack.key'] = process.env.bs_key;
    browserstack.capabilities['browserstack.local'] = 'true';

    return {
        configList: [
            /* OS X / Chrome. */
            protractorUtils.mergeConfig({
                configList: [
                    protractorBaseConfig,
                    browserstack,
                    protractorUtils.os.osx,
                    protractorUtils.browser.chrome
                ]
            }),
            // /* OS X / Safari. */
            // protractorUtils.mergeConfig({
            //     configList: [
            //         protractorBaseConfig,

baseUrl: env.baseUrl + '/ng1/',

  jasmineNodeOpts: {
    isVerbose: true,
    realtimeFailure: true
  },

  params: {
    login: {
      user: 'Jane',
      password: '1234'
    }
  }
};
exports.config.capabilities['browserstack.local'] = true;

capList.forEach(function (cap) {
            cap["browserstack.user"] = "winjsproject";
            cap["browserstack.key"] = "scb8Tm2t5saetT1KzPBd";
            cap["browserstack.local"] = true;
        });