    def save(self):
        filename_list = self.output['source']['filenames']
        if not isinstance(filename_list, list):
            filename_list = filename_list.split(' ')
        contents_list = []
        for filename in filename_list:
            file_path = os.path.join(
                self.working_dir, filename)
            contents_list.append(self._read_file(file_path))
        self.output.update({'data': {'contents': contents_list}})
        self.connection.update_task_attempt_output(
            self.output['uuid'],
            self.output)