code: def test_loss_dense(self):
      pos = torch.tensor(
          [[[0, 0, 0], [1, 0, 0], [1.1, 0, 0]]], dtype=torch.float
      )
      f = torch.tensor([[1, 1, 3]], dtype=torch.float)
  
      var = _variance_estimator_dense(1.01, pos, f)
      torch.testing.assert_allclose(var, [[0, 4, 4]])
  
      loss = dirichlet_loss(1.01, pos, f)
      self.assertAlmostEqual(loss.item(), 4 / 3.0)
  
file_path: torch-points3d/test/test_losses.py
imports: import unittest
  import torch
  import os
  import sys
  from torch_points3d.core.losses.dirichlet_loss import _variance_estimator_dense, dirichlet_loss, _variance_estimator_sparse
label_desc: Use image node_id 1 for calling the TestDirichletLoss obj's underlying member method code with example usage: obj.test_loss_dense() without return types