Calculate mangitude (of vector) in programmable filter

I would like to calculate magnitude of a vector in the programmable filter. It’s possible to use the expression mag(U) in the python calculator filter but there is one drawback. However, python calculator can only take one vector at a time. I have two vectors (U, shearStress), the magnitude of which I want to calculate individually, with a single filter (in the programmable filter) as python calculator or calculator can’t do that.

Can someone please let me know what should be the expression to calculate a vector magnitude?

Without this, my workflow fails. I can access the vectors like this: Vectors in Programmable Filter. I use programmable filter for exporting dataset at multiple timepoints: Reveal underlying codes when executing commands in the paraView GUI.