code: def _list_outputs(self):
      outputs = self._outputs().get()
      outputs["output1"] = [1, self.inputs.input1]
      return outputs
  
imports: import sys
  import os
  import pytest
  from nipype.pipeline import engine
  from nipype.interfaces import base
label_desc: Use image node_id 2 for calling the MultiprocTestInterface obj's underlying member method code with example usage: obj._list_outputs() and returns: outputs