code: def test_default_epoch(self):
      metric = MetricList(["epoch"])
      self.assertTrue(
          metric.metric_list[0].name == "epoch",
          msg="loss not in: " + str(metric.metric_list),
      )
  
imports: import unittest
  from mock import Mock
  from torchbearer.metrics import MetricList, Metric, MetricTree, AdvancedMetric
label_desc: Use image node_id 4 for calling the TestMetricList obj's underlying member method code with example usage: obj.test_default_epoch() without return types