code: def transform(self, trans):
          
          if isinstance(trans, vtk.vtkMatrix4x4):
              t = vtki.trans_from_matrix(trans)
          elif isinstance(trans, vtk.vtkTransform):
              t = vtki.trans_from_matrix(trans.GetMatrix())
          elif isinstance(trans, np.ndarray):
              if trans.shape[0] != 4 or trans.shape[1] != 4:
                  raise Exception('Transformation array must be 4x4')
              t = trans
          else:
              raise TypeError('Input transform must be either:\n'
                              + '\tvtk.vtkMatrix4x4\n'
                              + '\tvtk.vtkTransform\n'
                              + '\t4x4 np.ndarray\n')
  
          x = (self.points*t[0, :3]).sum(1) + t[0, -1]
          y = (self.points*t[1, :3]).sum(1) + t[1, -1]
          z = (self.points*t[2, :3]).sum(1) + t[2, -1]
  
          # overwrite points
          self.points[:, 0] = x
          self.points[:, 1] = y
          self.points[:, 2] = z
docs: Compute a transformation in place using a 4x4 transform.
  
          Parameters
          ----------
          trans : vtk.vtkMatrix4x4, vtk.vtkTransform, or np.ndarray
              Accepts a vtk transformation object or a 4x4 transformation matrix.