code: def setUp(self):
      self._metric = Metric("test")
      self._metric.process = Mock()
      self._metric.process.side_effect = [
          torch.zeros(torch.Size([])),
          torch.FloatTensor([0.1, 0.2, 0.3]),
          torch.FloatTensor([0.4, 0.5, 0.6]),
          torch.FloatTensor([0.7, 0.8, 0.9]),
          torch.ones(torch.Size([])),
      ]
  
      self._mean = Mean("test")
      self._mean.reset({})
      self._target = 0.5
  
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 1 for calling the TestMean obj's underlying member method code with example usage: obj.setUp() without return types