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from django.db import models
class Person(models.Model):
name = models.CharField(max_length=200)
class Movie(models.Model):
title = models.CharField(max_length=200)
director = models.ForeignKey(Person)
class Event(models.Model):
pass
class Screening(Event):
movie = models.ForeignKey(Movie)
class ScreeningNullFK(Event):
movie = models.ForeignKey(Movie, null=True)
class Package(models.Model):
screening = models.ForeignKey(Screening, null=True)
class PackageNullFK(models.Model):
screening = models.ForeignKey(ScreeningNullFK, null=True)
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