def METHOD_NAME(Base):
    class METHOD_NAME(Base):
        __tablename__ = 'employee'
        id = sa.Column(sa.Integer, primary_key=True)
        name = sa.Column(sa.String(50))
        type = sa.Column(sa.String(20))
        __mapper_args__ = {
            'polymorphic_on': type,
            'polymorphic_identity': 'employee'
        }
    return METHOD_NAME