code: def _list_outputs(self):
      outputs = self._outputs().get()
      outputs["output1"] = [1]
      return outputs
  
imports: import os
  from copy import deepcopy
  import pytest
  from ...None import engine
  from ....interfaces import base
  from ....interfaces import utility
  from ....None import config
  from ..utils import clean_working_directory, write_workflow_prov, load_resultfile, format_node
label_desc: Use image node_id 2 for calling the UtilsTestInterface obj's underlying member method code with example usage: obj._list_outputs() and returns: outputs