在跟着虫师的书一步一步的做的时候，出现了以下的问题：

 

 “HttpResponse” is not defined , so i need to modify the views.py in sign folder as bellow:

from django.shortcuts import render
from django.http import HttpResponse

# Create your views here.

def index(request):
        return HttpResponse("hello Djando!")

then execute again ,python3 manage.py runserver