code: def pointSize(self, s=None):
          
          if s is not None:
              if isinstance(self, vtk.vtkAssembly):
                  cl = vtk.vtkPropCollection()
                  self.GetActors(cl)
                  cl.InitTraversal()
                  a = vtk.vtkActor.SafeDownCast(cl.GetNextProp())
                  a.GetProperty().SetRepresentationToPoints()
                  a.GetProperty().SetPointSize(s)
              else:
                  self.GetProperty().SetRepresentationToPoints()
                  self.GetProperty().SetPointSize(s)
          else:
              return self.GetProperty().GetPointSize()
          return self
docs: Set/get actor's point size of vertices.