old_contents: from django.contrib import admin
  
  # Register your models here.
  
new_contents: from django.contrib import admin
  
  from models import (
      Feedback,
      FeedbackType,
      Attachment,
  )
  
  admin.site.register(Feedback)
  admin.site.register(FeedbackType)
  admin.site.register(Attachment)
  
subject: add admin