new_contents: from django.contrib import admin
  from django.contrib.contenttypes import models as ct_models
  
  from nodeconductor.quotas import models, utils
  
  
  class QuotaScopeClassListFilter(admin.SimpleListFilter):
      # Human-readable title
      title = 'Scope class'
  
      # Parameter for the filter that will be used in the URL query
      parameter_name = 'scope_class'
  
      def lookups(self, request, model_admin):
          models = utils.get_models_with_quotas()
          return [(ct_models.ContentType.objects.get_for_model(m).id, m.__name__) for m in models]
  
      def queryset(self, request, queryset):
          content_type_id = self.value()
          if content_type_id:
              return queryset.filter(content_type_id=content_type_id)
          return queryset
  
  
  class QuotaAdmin(admin.ModelAdmin):
      list_display = ['scope', 'name', 'limit', 'usage']
      list_filter = ['name', QuotaScopeClassListFilter]
  
  
  admin.site.register(models.Quota, QuotaAdmin)
  
subject: Implement admin model for quotas (nc-417)