code: def test_single_inheritance(self):
      class BaseClass(Versioned, self.Base, ComparableEntity):
          __tablename__ = "basetable"
  
          id = Column(Integer, primary_key=True)
          name = Column(String(50))
          type = Column(String(50))
          __mapper_args__ = {
              "polymorphic_on": type,
              "polymorphic_identity": "base",
          }
  
      class SubClass(BaseClass):
          subname = Column(String(50), unique=True)
          __mapper_args__ = {"polymorphic_identity": "sub"}
  
      self.create_tables()
      sess = self.session
  
      b1 = BaseClass(name="b1")
      sc = SubClass(name="s1", subname="sc1")
  
      sess.add_all([b1, sc])
  
      sess.commit()
  
      b1.name = "b1modified"
  
      BaseClassHistory = BaseClass.__history_mapper__.class_
      SubClassHistory = SubClass.__history_mapper__.class_
  
      eq_(
          sess.query(BaseClassHistory)
          .order_by(BaseClassHistory.id, BaseClassHistory.version)
          .all(),
          [BaseClassHistory(id=1, name="b1", type="base", version=1)],
      )
  
      sc.name = "s1modified"
      b1.name = "b1modified2"
  
      eq_(
          sess.query(BaseClassHistory)
          .order_by(BaseClassHistory.id, BaseClassHistory.version)
          .all(),
          [
              BaseClassHistory(id=1, name="b1", type="base", version=1),
              BaseClassHistory(
                  id=1, name="b1modified", type="base", version=2
              ),
              SubClassHistory(id=2, name="s1", type="sub", version=1),
          ],
      )
  
      # test the unique constraint on the subclass
      # column
      sc.name = "modifyagain"
      sess.flush()
  
imports: import unittest
  import warnings
  from sqlalchemy import Boolean
  from sqlalchemy import Column
  from sqlalchemy import create_engine
  from sqlalchemy import ForeignKey
  from sqlalchemy import inspect
  from sqlalchemy import Integer
  from sqlalchemy import join
  from sqlalchemy import select
  from sqlalchemy import String
  from sqlalchemy.orm import clear_mappers
  from sqlalchemy.orm import column_property
  from sqlalchemy.orm import declarative_base
  from sqlalchemy.orm import DeclarativeBase
  from sqlalchemy.orm import deferred
  from sqlalchemy.orm import exc
  from sqlalchemy.orm import relationship
  from sqlalchemy.orm import Session
  from sqlalchemy.testing import assert_raises
  from sqlalchemy.testing import AssertsCompiledSQL
  from sqlalchemy.testing import eq_
  from sqlalchemy.testing import eq_ignore_whitespace
  from sqlalchemy.testing import is_
  from sqlalchemy.testing import ne_
  from sqlalchemy.testing.entities import ComparableEntity
  from .history_meta import Versioned
  from .history_meta import versioned_session
label_desc: Use image node_id 14 for calling the TestVersioning obj's underlying member method code with example usage: obj.test_single_inheritance() without return types