code: def _add_context(self, message):
      return {
          k: v if k != "text" else CONTEXT + "\n" + v
          for k, v in message.items()
      }
  
imports: import unittest
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.teachers import create_task_agent_from_taskname
  from parlai.core.message import Message
label_desc: Use image node_id 3 for calling the TestSpecificMutators obj's underlying member method code with example usage: obj._add_context(message) and returns: unknown