dsdemo3 stuffABCD returns error

[nslton]

I tried running some of the dsdemo3, the parts relevant to generating the a,g,b,c coefficients. After I run "realizeNTF", the a,b,c,d coefficients match those shown on the dsdemo3 page (https://nbviewer.org/github/ggventurini/python-deltasigma/blob/master/examples/dsdemo3.ipynb) in the "Out[10]" line.

However once I run "ABCD = stuffABCD(a, g, b, c);" I get an error. I've attached the error and a picture of the source file, please help resolve. Thank you.