vtkSphere : passing a null parameter in ComputeBoundingSphere from Python

I’m not sure if there is a clean way to set default for a double[2] argument, so I fully agree that overload is a better approach in this case. In general, I’m not sure that overloads is always preferable (and if they are preferable then not because they are better for managing backward compatibility), but that’s a separate discussion topic in itself - so I’ve added a new topic for this: