old_contents: from django.db import models
  
  # Use get_user_model() to get the user model
  # i.e. do not import django.contrib.auth.models.User directly!
  # You can also use settings.AUTH_USER_MODEL, in ForeignKeys for example.
  from django.contrib.auth import get_user_model
  from django.conf import settings
  
  
  class NameDescriptionMixin(models.Model):
      """Inherit from this to add name/description fields"""
  
      class Meta:
          abstract = True
  
      name = models.CharField(max_length=150, default='')
      description = models.TextField(default='')
  
  
      def __str__(self):
      	return name
  
      def __unicode__(self):
      	return name
  
  
  class CreatedAtField(models.DateTimeField):
      """A datetime field that auto-nows automatically"""
  
      def __init__(self, *args, **kwargs):
          kwargs['auto_now'] = True
          super(CreatedAtField, self).__init__(*args, **kwargs)
  
new_contents: from django.db import models
  
  # Use get_user_model() to get the user model
  # i.e. do not import django.contrib.auth.models.User directly!
  # You can also use settings.AUTH_USER_MODEL, in ForeignKeys for example.
  from django.contrib.auth import get_user_model
  from django.conf import settings
  
  
  class NameDescriptionMixin(models.Model):
      """Inherit from this to add name/description fields"""
  
      class Meta:
          abstract = True
  
      name = models.CharField(max_length=150, default='')
      description = models.TextField(default='')
  
  
      def __str__(self):
      	return self.name
  
      def __unicode__(self):
      	return self.name
  
  
  class CreatedAtField(models.DateTimeField):
      """A datetime field that auto-nows automatically"""
  
      def __init__(self, *args, **kwargs):
          kwargs['auto_now'] = True
          super(CreatedAtField, self).__init__(*args, **kwargs)
  
subject: prepend name to get at the right variable