code: def testObserver(self):
      ob = self.model.net.AddObserver("TimeObserver")
      ws.RunNet(self.model.net)
      print(ob.average_time())
      num = self.model.net.NumObservers()
      self.model.net.RemoveObserver(ob)
      assert self.model.net.NumObservers() + 1 == num
  
file_path: pytorch/caffe2/python/observer_test.py
imports: import numpy
  import unittest
  from hypothesis import given, settings
  import hypothesis.strategies
  from caffe2.python import brew, core, model_helper, rnn_cell
  import caffe2.python.workspace
label_desc: Use image node_id 2 for calling the TestObservers obj's underlying member method code with example usage: obj.testObserver() without return types