code: def setup_mappers(cls):
      cls.mapper(
          Company,
          companies,
          properties={
              "employees": relationship(
                  Person, order_by=people.c.person_id
              )
          },
      )
  
      cls.mapper(Machine, machines)
  
      (
          person_with_polymorphic,
          manager_with_polymorphic,
      ) = cls._get_polymorphics()
  
      cls.mapper(
          Person,
          people,
          with_polymorphic=person_with_polymorphic,
          polymorphic_on=people.c.type,
          polymorphic_identity="person",
          properties={
              "paperwork": relationship(
                  Paperwork, order_by=paperwork.c.paperwork_id
              )
          },
      )
  
      cls.mapper(
          Engineer,
          engineers,
          inherits=Person,
          polymorphic_identity="engineer",
          properties={
              "company": relationship(Company, viewonly=True),
              "machines": relationship(
                  Machine, order_by=machines.c.machine_id
              ),
          },
      )
  
      cls.mapper(
          Manager,
          managers,
          with_polymorphic=manager_with_polymorphic,
          inherits=Person,
          polymorphic_identity="manager",
      )
  
      cls.mapper(
          Boss, boss, inherits=Manager, polymorphic_identity="boss"
      )
  
      cls.mapper(Paperwork, paperwork)
  
imports: from sqlalchemy import ForeignKey
  from sqlalchemy import Integer
  from sqlalchemy import String
  from sqlalchemy import util
  from sqlalchemy.orm import polymorphic_union
  from sqlalchemy.orm import relationship
  from sqlalchemy.orm import sessionmaker
  from sqlalchemy.sql.selectable import LABEL_STYLE_TABLENAME_PLUS_COL
  from sqlalchemy.testing import AssertsCompiledSQL
  from sqlalchemy.testing import config
  from sqlalchemy.testing import fixtures
  from sqlalchemy.testing.entities import ComparableEntity
  from sqlalchemy.testing.schema import Column
  from sqlalchemy.testing.schema import Table
label_desc: Use image node_id 7 for calling the _PolymorphicFixtureBase obj's underlying member method code with example usage: obj.setup_mappers(cls) without return types