code: def test_stn(self):
      pos = torch.tensor(
          [[1, 1, 2], [-1, 0, 1], [10, 12, 13], [-18, 15, 16]]
      ).to(torch.float32)
      batch = torch.tensor([0, 0, 1, 1])
  
      stn = PointNetSTN3D(batch_size=2)
  
      trans_pos = stn(pos, batch)
  
      npt.assert_array_equal(
          np.asarray(pos.detach()), np.asarray(trans_pos.detach())
      )
  
imports: import unittest
  import numpy
  import numpy.testing
  import torch
  import os
  import sys
  from collections import defaultdict
  from omegaconf import DictConfig
  from torch_points3d.models.base_model import BaseModel, BaseInternalLossModule
  from torch_points3d.modules.PointNet.modules import PointNetSTN3D
label_desc: Use image node_id 1 for calling the TestPointnetModules obj's underlying member method code with example usage: obj.test_stn() without return types