How to pass the output of a Reader to an algorithm or filter

I’m trying to use vtk functionality not available in paraview. So I’m trying to do everything I need to in a script and its a fairly long script so I don’t prefer the programmable script method.
My question is, how do I pass the output of say STLReader to an algorithm or filter? Example below.

boneScanReader = STLReader(registrationName = 'BoneScan')
boneScanReader.FileNames = tibiaSTLFile
boneScanReader.UpdatePipeline()
.
.
.
postImpactScanTransform = vtk.vtkTransformPolyDataFilter()
postImpactScanTransform.SetInputData(boneScanReader)

SetInputData() is where I’m having trouble. I don’t quite understand how to get the polygonal mesh from the STLReader

Unrelated.

You are confusing client side pvpython scripting and servser side VTKPython scripting.
https://kitware.github.io/paraview-docs/latest/python/
https://docs.paraview.org/en/latest/ReferenceManual/pythonProgrammableFilter.html

postImpactScanTransform.SetInputConnection(boneScanReader.GetOutputPort())