text: import  { createStackNavigator } from 'react-navigation-stack';
  import { createAppContainer } from 'react-navigation';
  import Login from '../screens/login';
  import Register from '../screens/register'
  
  const screens = {
      Login: {
          screen: Login
      }
  }
  const LoginStack = createStackNavigator(screens);
  
  export default createAppContainer(LoginStack);