code: def test_load_custom_operator_plugin(self):
      with self.assertRaises(AttributeError):
          print(ops.CustomDummy)
      load_empty_plugin()
      print(ops.CustomDummy)
  
imports: from nvidia.dali.pipeline import Pipeline
  import nvidia.dali
  import nvidia.dali.ops
  import nvidia.dali.plugin_manager
  import unittest
  import os
  import numpy
  import tempfile
label_desc: Use image node_id 4 for calling the TestLoadedPlugin obj's underlying member method code with example usage: obj.test_load_custom_operator_plugin() without return types