How to use the SelectExamples

I want to use the SelectExamples to look through some examples about vtk class which i need,but i don’t know where can modify the vtk_class and language,I ran the official example code directly and got the following error feedback:error: the following arguments are required: vtk_class, language.
so,what can i do

The two positional parameters that you must specify are the VTK class and language e,g. vtkPolyData Cxx, there are also some optional parameters.

where i can specify they two in official example?(in python language)

Try vtkPolyData and Python as parameters e.g.:

python3 vtkPolyData Python.

For help try:

python3 -h