    converter = vtkUnstructuredGridToExplicitStructuredGrid()
    converter.SetInputData(grid)
    converter.SetInputArrayToProcess(0, 0, 0, 1, 'BLOCK_I')
    converter.SetInputArrayToProcess(1, 0, 0, 1, 'BLOCK_J')
    converter.SetInputArrayToProcess(2, 0, 0, 1, 'BLOCK_K')
    converter.Update()
--
    converter = vtkUnstructuredGridToExplicitStructuredGrid()
    converter.GlobalWarningDisplayOff()  # hide VTK errors
    converter.SetInputConnection(reader.GetOutputPort())
    converter.SetInputArrayToProcess(0, 0, 0, 1, 'BLOCK_I')
    converter.SetInputArrayToProcess(1, 0, 0, 1, 'BLOCK_J')
    converter.SetInputArrayToProcess(2, 0, 0, 1, 'BLOCK_K')
