code: def testMovingAverageValueMeter(self):
      mtr = meter.MovingAverageValueMeter(3)
  
      mtr.add(1)
      avg, var = mtr.value()
  
      self.assertEqual(avg, 1.0)
      self.assertEqual(var, 0.0)
      mtr.add(3)
      avg, var = mtr.value()
      self.assertEqual(avg, 2.0)
      self.assertEqual(var, math.sqrt(2))
  
      mtr.add(5)
      avg, var = mtr.value()
      self.assertEqual(avg, 3.0)
      self.assertEqual(var, 2.0)
  
      mtr.add(4)
      avg, var = mtr.value()
      self.assertEqual(avg, 4.0)
      self.assertEqual(var, 1.0)
  
      mtr.add(0)
      avg, var = mtr.value()
      self.assertEqual(avg, 3.0)
      self.assertEqual(var, math.sqrt(7))
  
file_path: pywick/tests/test_meters.py
imports: import unittest
  import math
  import torch
  import pywick.meters
  import numpy
label_desc: Use image node_id 5 for calling the TestMeters obj's underlying member method code with example usage: obj.testMovingAverageValueMeter() without return types