      def save(self, *args, **kwargs):
          """For the purposes of the sandbox, limit the maximum number of stored models."""
          super(MyModel, self).save(*args, **kwargs)
          while MyModel.objects.all().count() > MAX_INSTANCES:
              MyModel.objects.all()[0].delete()
      
      @models.permalink
      def get_absolute_url(self):
          return ('my-model-resource', (self.pk,))
  
 
</s> remove         """For the purposes of the sandbox, limit the maximum number of stored models."""
 </s> add         """
        For the purposes of the sandbox limit the maximum number of stored models.
        """ </s> remove     
    class Meta:
        ordering = ('created',)
 </s> add  </s> remove     class Meta:
        ordering = ('created',)

    @models.permalink
    def get_absolute_url(self):
        return ('blog-post', (), {'key': self.key})

    @property
    @models.permalink
    def comments_url(self):
        """Link to a resource which lists all comments for this blog post."""
        return ('comments', (), {'blogpost': self.key})

    def __unicode__(self):
        return self.title

 </s> add  </s> remove         for obj in self.__class__.objects.order_by('-pk')[MAX_POSTS:]:
 </s> add         for obj in self.__class__.objects.order_by('-created')[MAX_POSTS:]: </s> remove         """Create a new highlighed snippet and return it's location.
        For the purposes of the sandbox example, also ensure we delete the oldest snippets if we have > MAX_FILES."""
 </s> add         """
        Create a new highlighed snippet and return it's location.
        For the purposes of the sandbox example, also ensure we delete the oldest snippets if we have > MAX_FILES.
        """
            MyModel.objects.all().order_by('-created')[0].delete()

      def save(self, *args, **kwargs):
          """For the purposes of the sandbox, limit the maximum number of stored models."""
          super(MyModel, self).save(*args, **kwargs)
          while MyModel.objects.all().count() > MAX_INSTANCES:
            MyModel.objects.all().order_by('-created')[0].delete()

            MyModel.objects.all().order_by('-created')[0].delete()

            MyModel.objects.all().order_by('-created')[0].delete()

            MyModel.objects.all().order_by('-created')[0].delete()

            MyModel.objects.all().order_by('-created')[0].delete()

  
keep keep keep keep replace replace replace replace replace keep
 Fixing some of the last blocking issues 
examples/modelresourceexample/models.py