old_contents: from django.core.management.base import BaseCommand
  
  from cyder.models import MODEL_LIST
  from cyder.base.models import ExpirableMixin
  
  from datetime import datetime
  
  
  class Command(BaseCommand):
      option_list = BaseCommand.option_list
  
      def handle(self, *args, **options):
          now = datetime.now()
          for model in MODEL_LIST:
              if issubclass(model, ExpirableMixin):
                  model.objects.filter(expire__lte=now).delete()
  
new_contents: from django.core.management.base import BaseCommand
  
  from cyder.models import MODEL_LIST
  from cyder.base.models import ExpirableMixin
  
  from datetime import datetime
  
  
  class Command(BaseCommand):
      option_list = BaseCommand.option_list
  
      def handle(self, *args, **options):
          now = datetime.now()
          for model in MODEL_LIST:
              if issubclass(model, ExpirableMixin):
                  objects = model.objects.filter(expire__lte=now)
                  for obj in objects:
                      obj.delete()
  
subject: use proper deletion for expired objects