To run and test the application, perform the following steps:

1. Open a Terminal at the root of your project directory and run:

      npm start

2. Then, open a new tab in your web browser and go to:

      http://localhost:1337/

3. The console in your browser will display the following warning:

      Warning: Failed prop type: "Toggle" expected children to contain exactly 2 React       elements 
          in Toggle (created by App) 
          in App 

4. Clicking the button will toggle between the first two React elements while the third React element will be ignored