text: from django.db import models
  from unixtimestampfield import UnixTimeStampField
  
  
  class RecordsQuerySet(models.QuerySet):
      """
      QS that helps to separate deleted records from present
      in all inherited models.
      """
  
      def present(self):
          return self.filter(deleted=False)
  
      def deleted(self):
          return self.filter(deleted=True)
  
  
  class DatedModel(models.Model):
      created_at = UnixTimeStampField(auto_now_add=True, use_numeric=True)
      updated_at = UnixTimeStampField(auto_now_add=True, auto_now=True,
                                      use_numeric=True)
      deleted = models.BooleanField(default=False)
  
      objects = RecordsQuerySet.as_manager()
  
      class Meta:
          abstract = True
          ordering = ('id',)
  