In the next lecture, we'll add react-navigation.

I'm still using v3 of that package in the next lectures - you will be using v4 if you install it via npm install --save react-navigation.

That's fine, just keep in mind that you need to import createStackNavigator differently.

Instead of

import { createAppContainer, createStackNavigator } from 'react-navigation';

you'll need to install an extra package:

npm install --save react-navigation-stack

and then import like this:

import { createAppContainer } from 'react-navigation';
import { createStackNavigator } from 'react-navigation-stack';