Hey,
So I had a look at it and I think that the API has changed since the Python was written…
http://www.revitapidocs.com/2018/109fddb7-82a5-31b7-9334-54a876fab07b.htm
There doesn’t appear to be a Curve property any more, so I presume that we now need the GetCurve method, and because it’s a method, rather than a property, it needs to be GetCurve()
The downside to using Python rather than nodes 
(that someone else will keep updated)
Hope that helps,
Mark