Nothing shown on the screen - tutorial 4

I ran server and accessed to 'http://127.0.0.1:8000/'.
But nothing displayed on screen.
And it loads perpetually.
![에러 화면 캡처](https://user-images.githubusercontent.com/49196380/129525483-66c5f0d8-be95-4658-afda-35b47c6f7552.PNG)

I ran python server in  a pipenv environment.