Endpoint: /album/<album_id>/cover/<photo_id>/update.json

        Update the cover photo of this album.

def cover_update(self, photo, **kwds):
        """
        Endpoint: /album/<album_id>/cover/<photo_id>/update.json

        Update the cover photo of this album.
        """
        result = self._client.album.cover_update(self, photo, **kwds)
        self._replace_fields(result.get_fields())
        self._update_fields_with_objects()