old_contents: # -*- coding: utf-8 -*-
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  
  class Category(models.Model):
      name = models.CharField(_('title'), max_length=255)
  
      class Meta:
          verbose_name = _('category')
          verbose_name_plural = _('categories')
  
  
  class Post(models.Model):
      title = models.CharField(_('title'), max_length=255)
      body = models.TextField(blank=True)
  
      category = models.ForeignKey(
          Category,
          verbose_name=_('category'),
          null=True)
  
      class Meta:
          verbose_name = _('post')
          verbose_name_plural = _('posts')
  
new_contents: # -*- coding: utf-8 -*-
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  from linguist.mixins import LinguistMixin
  
  
  class Category(models.Model, LinguistMixin):
      name = models.CharField(_('title'), max_length=255)
  
      class Meta:
          verbose_name = _('category')
          verbose_name_plural = _('categories')
  
  
  class Post(models.Model, LinguistMixin):
      title = models.CharField(_('title'), max_length=255)
      body = models.TextField(blank=True)
  
      category = models.ForeignKey(
          Category,
          verbose_name=_('category'),
          null=True)
  
      class Meta:
          verbose_name = _('post')
          verbose_name_plural = _('posts')
  
subject: Update example models.