def get_session(backend_name, **options):
    global _default_session

    if not _default_session:
        _default_session = {}
        pool = ConnectionPool(factory=Connection,
                backend=backend_name, **options)
        _default_session[backend_name] = pool
    else:
        if _default_session not in backend_name:
            pool = ConnectionPool(factory=Connection,
                backend=backend_name, **options)

            _default_session[backend_name] = pool
        else:
            pool = _default_session.get(backend_name)
    return pool
dataset/ETHPy150Open benoitc/restkit/restkit/session.py/get_session/swapped operands of `not in`