text: from django.db import models
  
  
  class AdjacencyListModel(models.Model):
  
      title = models.CharField(max_length=100)
  
      parent = models.ForeignKey(
          'self', related_name='%(class)s_parent', on_delete=models.CASCADE, db_index=True, null=True, blank=True)
  
      def __str__(self):
          return 'adjacencylistmodel_%s' % self.title
  
  
  class NestedSetModel(models.Model):
  
      title = models.CharField(max_length=100)
  
      lft = models.IntegerField(db_index=True)
      rgt = models.IntegerField(db_index=True)
      level = models.IntegerField(db_index=True)
  
      def __str__(self):
          return 'nestedsetmodel_%s' % self.title
  