Thank you for catching this mistake in walkthrough 2 -- the issue has been corrected (as well the incorrect reference to d node as well). Originally, the 5-node circuit that one creates earlier was to be used for the compilation example, but the 3-node circuit was later created as a simpler/clearer example and the text/code snippets weren't completely updated to reflect the change.

Again, thanks for pointing this out -- the walkthrough 2 should now compile correctly and not refer to any absent/non-existent c (or even d) node now.

Really happy to hear you are enjoying the library and we really appreciate the error/bug catching!