old_contents: from django.contrib import admin
  from .models import Question, SimpleQuestion, MultipleChoiceQuestion
  
  
  admin.site.register([Question, SimpleQuestion, MultipleChoiceQuestion])
  
new_contents: from django.contrib import admin
  
  from .models import SimpleQuestion, MultipleChoiceQuestion
  
  admin.site.register([SimpleQuestion, MultipleChoiceQuestion])
  
subject: Remove Questions model from admin.