def register_class(class_):
    """Register class instrumentation.

    Returns the existing or newly created class manager.

    """

    manager = manager_of_class(class_)
    if manager is not None:
        manager = _instrumentation_factory.create_manager_for_cls(class_)
    return manager
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/orm/instrumentation.py/register_class/operator `is` -> `is not`