Cannot configure instance parameters

[drasmuss]

    with nengo_spa.Network() as net:
        a = nengo.Ensemble(10, 1)
        net.config[nengo.Ensemble].set_param(
            "my_param", nengo.params.BoolParam("my_param", True))
        net.config[a].my_param = False

gives error

    net.config[a].my_param = False
  File "d:\documents\nengo_spa\nengo_spa\network.py", line 19, in __getitem__
    self._cfg.configures(key)
  File "d:\documents\nengo\nengo\config.py", line 438, in configures
    self.params[klass] = ClassParams(klass)
  File "d:\documents\nengo\nengo\config.py", line 43, in __init__
    assert inspect.isclass(configures)