text: 
  //this file is the main component of our app, and that's a router from react-navigation
  import React, { Component } from 'react';
  import { Root, Main } from './config/router';
  
  //all components in react native are extended from Component class of react
  //this is also mandatory for all things we consider a react-native component in our app
  class App extends Component {
    //besides the definition from documentation, there's nothing else more to say about render method
    //it is, again, mandatory and has to return always something
    //if we don't want to return anything, then we simply return an empty view component <View/>
    render() {
      return <Root />;
    }
  }
  
  //we can define multiple components in the same file and is not mandatory to export all of them
  //in this case, of course we export de App component since we need it in the index.android.js
  //but we could have also created multiple components here in the same file, use it alse here in the render method,
  //and we didn't have to export them in order for our app to work
  
  export default App;