code: def test_exception(self):
      if sys.version_info[0] < 3:
          self.assertRaises(Exception, PyCM)
  
imports: import sys
  from unittest import TestCase
  from mock import MagicMock, patch, ANY
  import torchbearer
  from torchbearer.callbacks import PyCM
  import matplotlib.pyplot
label_desc: Use image node_id 1 for calling the TestPyCM obj's underlying member method code with example usage: obj.test_exception() without return types