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