code: def test_eval_mode(self):
      t = torch.rand(1, 1, 4, 4)
      p = torch.nn.Conv2d(1, 1, 3)
      p.eval()
      self.assertFalse(p.training)  # False
      with train_mode(p):
          self.assertTrue(p.training)  # True
          p(t).sum().backward()
  
imports: from __future__ import annotations
  import unittest
  import torch
  from monai.networks.utils import train_mode
label_desc: Use image node_id 1 for calling the TestEvalMode obj's underlying member method code with example usage: obj.test_eval_mode() without return types