text: from django.db import models
  
  
  class Poll(models.Model):
      question = models.CharField(max_length=200)
  
  
  class Choice(models.Model):
      poll = models.ForeignKey(Poll, models.CASCADE)
      choice = models.CharField(max_length=200)
  
  
  # A set of models with an inner one pointing to two outer ones.
  
  
  class OuterA(models.Model):
      pass
  
  
  class OuterB(models.Model):
      data = models.CharField(max_length=10)
  
  
  class Inner(models.Model):
      first = models.ForeignKey(OuterA, models.CASCADE)
      # second would clash with the __second lookup.
      third = models.ForeignKey(OuterB, models.SET_NULL, null=True)
  