text: import { createAppContainer, createSwitchNavigator } from 'react-navigation';
  
  import Login from './pages/Login';
  import List from './pages/List';
  import Book from './pages/Book';
  
  
  const Routes = createAppContainer( 
    createSwitchNavigator({
        Login,
        List,
        Book
    })
  );
  
  export default Routes;