[vtkusers] questions about Update(), PrintSelf(), Print()

[Lenu C]

Hello all,

I've recently started using VTK in my research and I'm having troubles
understanding some of the concepts.
Here are two of the most recent questions I've not been successful in
answering myself:

1. Can someone give me a concrete example (in Python preferably) that
uses PrintSelf()? What about an example that uses  Print()?
2. Why does the execution time change when I use Update() method vs.
when I don't use it? The final image appears to be the same...

Thank you!
Lenu