Grigory

```python class Page(PolymorphicMPTTModel): parent = PolymorphicTreeForeignKey( to='self', blank=True, null=True, related_name='children', verbose_name='parent', on_delete=models.CASCADE ) title = models.CharField('Title', max_length=100) is_public = models.BooleanField(default=True) class HTMLPage(Page): pass class TypedPage(Page): pass ``` ```python page =...