old_contents: from django.contrib import admin
  
  from .models import VirtualMachine
  # Register your models here.
  
  admin.site.register(VirtualMachine)
  admin.site.register(VirtualMachineHost)
  
new_contents: from django.contrib import admin
  
  from .models import VirtualMachine, VirtualMachineHost
  # Register your models here.
  
  admin.site.register(VirtualMachine)
  admin.site.register(VirtualMachineHost)
  
subject: add missing import