code: def test_opt_step(self):
      self._test_opt_step_opts(1)
  
imports: import os
  import unittest
  import json
  import parlai.utils.logging
  import parlai.utils.testing
  from parlai.utils.io import PathManager
  from parlai.core.metrics import AverageMetric
  from parlai.core.worlds import create_task
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.core.agents import register_agent, Agent
  from parlai.scripts.eval_model import get_task_world_logs
label_desc: Use image node_id 7 for calling the TestTrainModel obj's underlying member method code with example usage: obj.test_opt_step() without return types