code: def test_nested_epoch_metrics(self):
      actual = rename_doubles([], [["a", "a"]])
      expected = [], [["a1", "a2"]]
      self.assertEqual(expected, actual)
  
      actual = rename_doubles([], [["a", "b"], "b"])
      expected = [], [["a", "b1"], "b2"]
      self.assertEqual(expected, actual)
  
imports: import os
  import unittest
  from unittest import skipIf
  from unittest.mock import ANY
  import numpy
  import torch
  import torch.nn
  import torchmetrics
  from poutyne import Metric, Model, do_register_metric_class, rename_doubles, unregister_metric_class
label_desc: Use image node_id 4 for calling the MetricsRenamingTest obj's underlying member method code with example usage: obj.test_nested_epoch_metrics() without return types