How to use the backendless.initApp function in backendless

/// 

import {Component} from '@angular/core';
import {Platform, AlertController} from "ionic-angular";
import {StatusBar, Push, Splashscreen, Device} from "ionic-native";

import {HomePage} from '../pages/home/home';


import Backendless from "backendless";

const APP_ID: string = 'YOUR_APPLICATION_ID';
const APP_KEY: string = 'YOUR_APPLICATION_KEY';

Backendless.initApp(APP_ID, APP_KEY);

@Component({
  templateUrl: 'app.html'
})
export class MyApp {
  rootPage = HomePage;

  constructor(public platform: Platform,
              public alertCtrl: AlertController) {
    platform.ready().then(() => {
      // Okay, so the platform is ready and our plugins are available.
      // Here you can do any higher level native things you might need.
      StatusBar.styleDefault();
      Splashscreen.hide();

      this.initPushNotification();

AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';

import PushNotification from 'react-native-push-notification';

import DeviceInfo from 'react-native-device-info';

import Backendless from 'backendless';

const APP_ID = 'YOUR_APPLICATION_ID';
const APP_KEY = 'YOUR_APPLICATION_KEY';

Backendless.initApp(APP_ID, APP_KEY);

PushNotification.configure({

  // (optional) Called when Token is generated (iOS and Android)
  onRegister: function(device) {
    Backendless.setupDevice({
      uuid    : DeviceInfo.getUniqueID(),
      platform: device.os,
      version : DeviceInfo.getSystemVersion()
    });

    Backendless.Messaging.registerDevice(device.token).then(
      function() {
        alert("Registration done");
      },
      function() {