How to set post render callback, python tab missing from node

Software Natron
1

The documentation shows a python tab for a write node within which I can add a callback function.
https://natron.readthedocs.io/en/rb-2.5/devel/callbacks.html#the-after-render-callback
This is my write node
image
Am I doing something wrong?

2

I guess I should add. Windows 10 64
Natron version 2.4.1 Release.

3

image
Never mind, I am blind as a bat
Appears to be in the Node tab now