RhinoScript Editor IsNull not showing as function

I am working through a tutorial and the IsNull command is not showing blue within the editor unlike the pdf tutorial. I think this is causing an endless increment, that I can esc. out of, which makes me unsure that it is not working as It is my understanding that esc. represents null.-Mike

Esc does not necessarily represent Null, it simply tells the method that you want to abort. What the method does with that actually depends on how the method is designed - but in most cases these methods are designed to return Null if you hit Esc without doing anything.

So, Rhino.GetString should return Null if Esc is pressed. Therefore the problem most likely lies elsewhere. Without seeing the whole Do loop and the various inputs, it’s hard to tell where it’s going wrong though.

–Mitch

IsNull works fine, I just did not have a good understanding and should have looked further into it. I am gathering some of scripts in the 101 tutorials are printed to be modified by user to better understand the case at hand.
Thanks again-Mike