[Paraview] how-to use vtkCleanUnstructuredGrid?

[jean mensa]

Hi all,
I am trying to clean an unstructured mesh with a python script and I
want to use the vtkCleanUnstructuredGrid() filter.
What I have now is something that looks like this,

ugrid = vtk.vtkUnstructuredGrid()
gridreader = vtk.vtkXMLUnstructuredGridReader()
gridreader.SetFileName(filename)
gridreader.Update()
ugrid = self.gridreader.GetOutput()

but now I am stuck. How do I apply the filter? and also, where do I
find vtkCleanUnstructuredGrid()?? It doesn't seem to be in any of the
pv classes...
Thank you!
j