code: def _fetch_data(self):
          
          if (self.inputs.surface_target == "fsnative" or
                  self.inputs.volume_target != "MNI152NLin2009cAsym"):
              # subject space is not support yet
              raise NotImplementedError
  
          annotation_files = sorted(glob(os.path.join(self.inputs.subjects_dir,
                                                      self.inputs.surface_target,
                                                      'label',
                                                      '*h.aparc.annot')))
          if not annotation_files:
              raise IOError("Freesurfer annotations for %s not found in %s" % (
                            self.inputs.surface_target, self.inputs.subjects_dir))
  
          label_file = str(get_template(
              'MNI152NLin2009cAsym', resolution=2, desc='DKT31', suffix='dseg'))
          return annotation_files, label_file
docs: Converts inputspec to files