code: def testAverageValueMeter(self):
      m = meter.AverageValueMeter()
      for i in range(1, 10):
          m.add(i)
      mean, std = m.value()
      self.assertEqual(mean, 5.0)
      m.reset()
      mean, std = m.value()
  
      self.assertTrue(np.isnan(mean))
  
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 1 for calling the TestMeters obj's underlying member method code with example usage: obj.testAverageValueMeter() without return types