code: def test_return_nan(
      metric,
      load_mnist_model_tf,
      load_mnist_images_tf,
      mock_prediction_changed,
  ):
      x_batch = load_mnist_images_tf["x_batch"]
      y_batch = predict(load_mnist_model_tf, x_batch)
  
      rs = metric()
      result = rs(
          model=load_mnist_model_tf,
          x_batch=x_batch,
          y_batch=y_batch,
          explain_func=explain,
      )
      assert np.isnan(result).any(), "Test Failed"
  
file_path: Quantus/tests/metrics/test_relative_stability.py
imports: from __future__ import annotations
  import pytest
  import torch
  from pytest_lazyfixture import lazy_fixture
  from typing import Dict, TYPE_CHECKING
  import functools
  from quantus.functions.perturb_func import *
  from quantus.functions.explanation_func import explain
  from quantus.metrics.robustness import RelativeInputStability, RelativeOutputStability, RelativeRepresentationStability
label_desc: Use image node_id 5 for calling a global function with example usage: test_return_nan(metric, load_mnist_model_tf, load_mnist_images_tf, mock_prediction_changed) without return types