code: def test_display_data_with_prepend_gold(self):
      parser = setup_args()
      opt = parser.parse_args(
          [
              "--task",
              "wizard_of_internet:WizardDialogGoldKnowledgeTeacher",
          ]
      )
      for out_type in display_data(opt):
          started_knowledge_span = False
          for token in [
              w.strip() for w in out_type.split() if w.strip()
          ]:
              if token == CONST.KNOWLEDGE_TOKEN:
                  self.assertFalse(started_knowledge_span)
                  started_knowledge_span = True
              elif token == CONST.END_KNOWLEDGE_TOKEN:
                  self.assertTrue(started_knowledge_span)
                  started_knowledge_span = False
  
          self.assertFalse(started_knowledge_span)
  
imports: import unittest
  from parlai.scripts.display_data import setup_args
  from parlai.utils.testing import display_data
  import parlai.tasks.wizard_of_internet.constants
  from parlai.core.message import Message
  from parlai.core.teachers import create_task_agent_from_taskname
label_desc: Use image node_id 2 for calling the TestWizardDialogTeacher obj's underlying member method code with example usage: obj.test_display_data_with_prepend_gold() without return types