code: def _upgrade_fixture(self):
      (
          users,
          Keyword,
          items,
          order_items,
          orders,
          Item,
          User,
          Address,
          keywords,
          item_keywords,
          Order,
          addresses,
      ) = (
          self.tables.users,
          self.classes.Keyword,
          self.tables.items,
          self.tables.order_items,
          self.tables.orders,
          self.classes.Item,
          self.classes.User,
          self.classes.Address,
          self.tables.keywords,
          self.tables.item_keywords,
          self.classes.Order,
          self.tables.addresses,
      )
  
      self.mapper_registry.map_imperatively(Address, addresses)
  
      self.mapper_registry.map_imperatively(Keyword, keywords)
  
      self.mapper_registry.map_imperatively(
          Item,
          items,
          properties=dict(
              keywords=relationship(
                  Keyword,
                  secondary=item_keywords,
                  lazy="select",
                  order_by=item_keywords.c.keyword_id,
              )
          ),
      )
  
      self.mapper_registry.map_imperatively(
          Order,
          orders,
          properties=dict(
              items=relationship(
                  Item,
                  secondary=order_items,
                  lazy=True,
                  order_by=order_items.c.item_id,
              )
          ),
      )
  
      self.mapper_registry.map_imperatively(
          User,
          users,
          properties=dict(
              addresses=relationship(
                  Address, lazy=True, order_by=addresses.c.id
              ),
              orders=relationship(Order, order_by=orders.c.id),
          ),
      )
  
      return fixture_session()
  
imports: import sqlalchemy
  from sqlalchemy import testing
  from sqlalchemy import util
  from sqlalchemy.orm import defaultload
  from sqlalchemy.orm import joinedload
  from sqlalchemy.orm import relationship
  from sqlalchemy.orm import subqueryload
  from sqlalchemy.testing import eq_
  from sqlalchemy.testing.assertions import expect_raises_message
  from sqlalchemy.testing.fixtures import fixture_session
  from test.orm import _fixtures
label_desc: Use image node_id 4 for calling the DefaultStrategyOptionsTest obj's underlying member method code with example usage: obj._upgrade_fixture() and returns: fixture_session