[Paraview] Some Filter with a programmable Filter combined

[no name]

Hello, I want to import the output of an already applied Filter in my
paraview programmable filter.

I load an INP file, use GradientOfUnstructuredDataSet1 on it with
output name "grad".

Now I want to apply a Programmable Filter on that
GradientOfUnstructuredDataSet1 and get it's values.

I can access them in the console by:

print grad.PointData.GetArray('dataX').GetRange()
print grad.PointData.GetArray('dataY').GetRange()
print grad.PointData.GetArray('dataZ').GetRange()

But in the Programmable filter I failed. I tried to fetch the data
with something similar to:

data = input(0,1) and so, but failed.

How do I adress this data best? I can get it Working in the console,
but not in the filter itself :(

Thanks
Richard