code: def test_train(self):
      result = self._mean._process_train(
          torch.FloatTensor([1.0, 1.5, 2.0])
      )
      self.assertAlmostEqual(self._target, result, 3, 0.002)
  
imports: import unittest
  from mock import Mock, call
  from torchbearer.metrics import RunningMean, Metric, RunningMetric, Mean, Std, Var
  import torch
label_desc: Use image node_id 2 for calling the TestRunningMean obj's underlying member method code with example usage: obj.test_train() without return types