Thank you for pointing out the issue with that example!
There are quite a few Nengo examples located in various places and we are working on consolidating and updating these examples to the latest versions of Nengo (it will take some time, we are a small team ), so we apologize for not getting to your issue quickly. Regardless, it was great that you reported your issue here as well as these forums are much more closely monitored.
As for the issue you are experiencing with the example, I’ve posted an in-depth response on Github on how to fix the issues to get it to run with the latest versions of Nengo.
A short summary of the issue is that we’ve modified how the
nengo.Sigmoid neuron behaves (this change was made in Nengo v2.4.0), and some parameters in the example notebook has to be updated to get it to work properly.