code: def _map_scratch_files(self, file_dict):
          
          if self._file_stage is None:
              return ({}, {})
          input_files = file_dict.input_files_to_stage
          output_files = file_dict.output_files_to_stage
          input_file_mapping = self._file_stage.map_files(input_files)
          output_file_mapping = self._file_stage.map_files(output_files)
          self._update_file_args(input_file_mapping)
          self._update_file_args(output_file_mapping)
          return input_file_mapping, output_file_mapping
docs: Build and return the mapping for copying files to and from scratch area