docs: def generate_donut():
      """Generate donut like shape with stick inside
  
      :return: dict {'data3d': '', 'segmentation': '', 'voxelsize_mm': ''}
      """
      segmentation = np.zeros([20, 30, 40])
      # generate test data
      segmentation[6:10, 7:24, 10:37] = 1
      segmentation[6:10, 7, 10] = 0
      segmentation[6:10, 23, 10] = 0
      segmentation[6:10, 7, 36] = 0
      segmentation[6:10, 23, 36] = 0
      segmentation[2:18, 12:19, 18:28] = 2
  
      data3d = segmentation * 100 + np.random.random(segmentation.shape) * 30
      voxelsize_mm = [3, 2, 1]
  
      datap = {
          "data3d": data3d,
          "segmentation": segmentation,
          "voxelsize_mm": voxelsize_mm,
      }
      # io3d.write(datap, "donut.pklz")
      return datap