    flyingEdges = vtkFlyingEdges2D()
    isoMapper = vtkPolyDataMapper()
    if useContouring:
        contour.SetInputConnection(extractVOI.GetOutputPort())
        contour.GenerateValues(12, scalarRange)
        isoMapper.SetInputConnection(contour.GetOutputPort())
--
    description = 'Either vtkFlyingEdges2D or vtkContourFilter is used to generate contour lines.'
    epilogue = '''
    Generate 2D contour lines, corresponding to tissue density, on one CT slice through the head.
    The contour lines are colored by the tissue density.
    '''
    parser = argparse.ArgumentParser(description=description, epilog=epilogue,
--
                        help='Use vtkContourFilter instead of vtkFlyingEdges2D.')
    args = parser.parse_args()
    return args.filename, args.useContouring


if __name__ == '__main__':
