code: def test_get_default_criterion_multiclass(
      self, mock_current_device, mock_is_available
  ):
      mock_current_device.return_value = "0"
      mock_is_available.return_value = True
  
      clf = SimplePytorchClassifier(3)
      class_weights = torch.ones(3)
      loss = clf._get_default_criterion(class_weights)
      self.assertTrue(isinstance(loss, CrossEntropyLoss))
  
imports: import pytest
  import unittest
  from unittest.mock import Mock, patch
  from small_text.integrations.pytorch.exceptions import PytorchNotFoundError
  from small_text.training.model_selection import ModelSelection, NoopModelSelection
  from tests.utils.datasets import random_text_classification_dataset
label_desc: Use image node_id 5 for calling the SimplePytorchClassifierTest obj's underlying member method code with example usage: obj.test_get_default_criterion_multiclass(mock_current_device, mock_is_available) without return types