I had a quick look through the example Dave. Bear in mind that I am brand new to python, have never worked with JSON and haven't done very much programming at all over the last few years.
Given all of that it looked quite straightforward, a testament to python's clarity. I am not sure I will take this approach though. My original observation was based on a belief that I couldn't run a decent python script from the server with parameters that could be adjusted by a non-programmer and therefore that I would need to use TCL on the server to run python on the switch ( I definitely wanted to move away from doing much in TCL ). I was wrong about that.
If I can use python on the server, that is preferred for me. We don't have a collection of existing python switch scripts that we would want to leverage. I am going to use python on the switch but it will be for port related scripting.
In any event, it's nice to have several options.