new_contents: from __future__ import unicode_literals
  
  from django.contrib.contenttypes.models import ContentType
  from django.core import serializers as django_serializers
  from django.core.management.base import BaseCommand
  from reversion.models import Version, Revision
  
  from nodeconductor.quotas import models
  from nodeconductor.quotas.utils import get_models_with_quotas
  
  
  class Command(BaseCommand):
      """ Recalculate all quotas """
  
      def handle(self, *args, **options):
          for model in get_models_with_quotas():
              if hasattr(model, 'GLOBAL_COUNT_QUOTA_NAME'):
                  quota, _ = models.Quota.objects.get_or_create(name=model.GLOBAL_COUNT_QUOTA_NAME)
                  for index, instance in enumerate(model.objects.all().order_by('created')):
                      revision = Revision.objects.create()
                      revision.date_created = instance.created
                      revision.save()
  
                      quota.usage = index + 1
                      serializer = django_serializers.get_serializer('json')()
                      serialized_data = serializer.serialize([quota])
  
                      Version.objects.create(
                          revision=revision,
                          object_id=quota.id,
                          object_id_int=quota.id,
                          content_type=ContentType.objects.get_for_model(quota),
                          format='json',
                          serialized_data=serialized_data,
                          object_repr=str(quota),
                      )
  
subject: Implement command for quotas history population