[1.3.X] Fixed #16000 -- reference natural keys in contenttypes documentation. Thanks jsdalton.

        :class:`~django.contrib.contenttypes.models.ContentType` instance

        representing that model.

    .. method:: get_by_natural_key(app_label, model)

        Returns the :class:`~django.contrib.contenttypes.models.ContentType`

        instance uniquely identified by the given application label and model

        name. The primary purpose of this method is to allow

        :class:`~django.contrib.contenttypes.models.ContentType` objects to be

        referenced via a :ref:`natural key<topics-serialization-natural-keys>`

        during deserialization.

The :meth:`~ContentTypeManager.get_for_model()` method is especially

useful when you know you need to work with a

:class:`ContentType <django.contrib.contenttypes.models.ContentType>` but don't

   should evaluate the models you expect to be pointing to and determine

   which solution will be most effective for your use case.

.. admonition:: Serializing references to ``ContentType`` objects

   If you're serializing data (for example, when generating

   :class:`~django.test.TestCase.fixtures`) from a model that implements

   generic relations, you should probably be using a natural key to uniquely

   identify related :class:`~django.contrib.contenttypes.models.ContentType`

   objects. See :ref:`natural keys<topics-serialization-natural-keys>` and

   :djadminopt:`dumpdata --natural <--natural>` for more information.

This will enable an API similar to the one used for a normal

:class:`~django.db.models.ForeignKey`;

each ``TaggedItem`` will have a ``content_object`` field that returns the