code: def test_no_train():
      """Assert that metric never leaves evaluation mode."""
  
      class MyModel(Module):
          def __init__(self) -> None:
              super().__init__()
              self.metric = FrechetInceptionDistance()
  
          def forward(self, x):
              return x
  
      model = MyModel()
      model.train()
      assert model.training
      assert (
          not model.metric.inception.training
      ), "FID metric was changed to training mode which should not happen"
  
imports: import pickle
  from contextlib import nullcontext
  from functools import partial
  import pytest
  import torch
  from torch.nn import Module
  from torch.utils.data import Dataset
  from torchmetrics.image.fid import FrechetInceptionDistance, NoTrainInceptionV3
  from torchmetrics.utilities.imports import _TORCH_FIDELITY_AVAILABLE
label_desc: Use image node_id 2 for calling a global function with example usage: test_no_train() and returns: x