text: # Abstract model classes that are common across apps.
  
  from django.db import models
  
  
  class Identified(models.Model):
      name = models.CharField(max_length=200)
      slug = models.SlugField(max_length=200, unique=True)
  
      @property
      def title(self):
          return self.name.capitalize()
  
      def __str__(self):
          return self.name
  
      class Meta:
          abstract = True
  
  
  class Described(Identified):
      description = models.TextField(null=True, blank=True)
  
      def __str__(self):
          return self.name
  
      class Meta:
          abstract = True
  
  
  class TimeStamped(models.Model):
      created_on = models.DateTimeField(auto_now_add=True)
      last_updated = models.DateTimeField(auto_now=True)
  
      class Meta:
          abstract = True