[Paraview] multiple inputs for python calculator filter

[Brandon, Mark]

I have been experimenting with the python calculator in Paraview 3.10.1, using the examples at the wiki page http://www.vtk.org/Wiki/ParaView/Users_Guide/Python_Calculator.
In particular, I was trying to figure out how to calculate the difference between two 3D point arrays. The sections on Accessing Data and Comparing Multiple Datasets seem to provide all that is needed to do this task.
However, I found the instructions there to be incomplete. It took me several hours to figure out that one has to highlight in the pipeline those multiple inputs you want to use before selecting the PythonCalculator filter.
In other words, the variables inputs[0], inputs[1], etc refer to the first of the highlighted pipeline entries, the second entry, etc.
It would be really helpful if the wiki included a full worked example, with this information as well.
Best,
Mark