old_contents: from django.contrib import admin
  
  from users.models import Lageruser, Department
  
  
  admin.site.register(Lageruser)
  admin.site.register(Department)
new_contents: from django.contrib import admin
  
  from users.models import Lageruser, Department, DepartmentUser
  
  
  admin.site.register(Lageruser)
  admin.site.register(Department)
  admin.site.register(DepartmentUser)
subject: Add DepartmentUser to admin interface