Fixed an inappropriate repetition. Thanks DanGer for the report.

<django.db.models.Field.null>`, the object will have ``get_next_by_FOO()`` and

``get_previous_by_FOO()`` methods, where ``FOO`` is the name of the field. This

returns the next and previous object with respect to the date field, raising

the appropriate :exc:`~django.db.DoesNotExist` exception when appropriate.

a :exc:`~django.db.DoesNotExist` exception when appropriate.

Both methods accept optional keyword arguments, which should be in the format

described in :ref:`Field lookups <field-lookups>`.