old_contents: # -*- coding: utf-8 -*-
  from __future__ import division, absolute_import, unicode_literals
  
  import datetime
  
  from django.db import models
  from django.utils import timezone
  from django.utils.encoding import python_2_unicode_compatible
  from django.utils.translation import ugettext_lazy as _
  
  
  @python_2_unicode_compatible
  class Poll(models.Model):
      question = models.CharField(max_length=200, verbose_name=_('question'))
      pub_date = models.DateTimeField(verbose_name=_('date published'))
  
      def __str__(self):
          return self.question
  
      def was_published_recently(self):
          return self.pub_date >= timezone.now() - datetime.timedelta(days=1)
      was_published_recently.admin_order_field = 'pub_date'
      was_published_recently.boolean = True
      was_published_recently.short_description = _('Published recently?')
  
      class Meta:
          verbose_name = _('poll')
          verbose_name_plural = _('polls')
  
  
  @python_2_unicode_compatible
  class Choice(models.Model):
      poll = models.ForeignKey(Poll, verbose_name=_('poll'))
      choice_text = models.CharField(
          max_length=200, verbose_name=_('choice text'))
      votes = models.IntegerField(default=0, verbose_name=_('votes'))
  
      def __str__(self):
          return self.choice_text
  
      class Meta:
          verbose_name = _('choice')
          verbose_name_plural = _('choices')
  
new_contents: # -*- coding: utf-8 -*-
  from __future__ import division, absolute_import, unicode_literals
  
  import datetime
  
  from django.db import models
  from django.utils import timezone
  from django.utils.encoding import python_2_unicode_compatible
  from django.utils.translation import ugettext_lazy as _
  
  
  @python_2_unicode_compatible
  class Poll(models.Model):
      question = models.CharField(max_length=200, verbose_name=_('question'))
      pub_date = models.DateTimeField(verbose_name=_('date published'))
  
      def __str__(self):
          return self.question
  
      def was_published_recently(self):
          return self.pub_date >= timezone.now() - datetime.timedelta(days=1)
      was_published_recently.admin_order_field = 'pub_date'
      was_published_recently.boolean = True
      was_published_recently.short_description = _('Published recently?')
  
      class Meta:
          verbose_name = _('poll')
          verbose_name_plural = _('polls')
  
  
  @python_2_unicode_compatible
  class Choice(models.Model):
      poll = models.ForeignKey(
          Poll,
          verbose_name=_('poll'),
          on_delete=models.CASCADE
      )
      choice_text = models.CharField(
          max_length=200, verbose_name=_('choice text'))
      votes = models.IntegerField(default=0, verbose_name=_('votes'))
  
      def __str__(self):
          return self.choice_text
  
      class Meta:
          verbose_name = _('choice')
          verbose_name_plural = _('choices')
  
subject: add on_delete positional arg to related fields