docs: def update(self, instance, validated_data):
          """Update ``Relation``."""
          # `partitions` field is renamed to `relationpartition_set` based on source of nested serializer
          partitions = validated_data.pop('relationpartition_set', None)
  
          with transaction.atomic():
              instance = super().update(instance, validated_data)
  
              if partitions is not None:
                  # TODO: Apply the diff instead of recreating all objects.
                  instance.relationpartition_set.all().delete()
                  self._create_partitions(instance, partitions)
  
          return instance