class_docstr: Calculates the error (distance) map between two input volumes.
  
  Example
  -------
  
  >>> errormap = ErrorMap()
  >>> errormap.inputs.in_ref = 'cont1.nii'
  >>> errormap.inputs.in_tst = 'cont2.nii'
  >>> res = errormap.run() # doctest: +SKIP
code: def _list_outputs(self):
      outputs = self.output_spec().get()
      outputs["out_map"] = self._out_file
      outputs["distance"] = self._distance
      return outputs
  
imports: import os
  import os.path
  import nibabel
  import numpy
  from ..None import config, logging
  from ..interfaces.base import SimpleInterface, BaseInterface, traits, TraitedSpec, File, InputMultiPath, BaseInterfaceInputSpec, isdefined
  from ..interfaces.nipy.base import NipyBaseInterface
label_desc: Use image node_id 2 for calling the ErrorMap obj's underlying member method code with example usage: obj._list_outputs() and returns: outputs