code: def identify_raw_files(task: Task, test_mode: bool = False) -> List[str]:
      
      raw_files = set()
      all_sets = [task.test,] if test_mode else [task.train, task.dev, task.test]
      for file_sets in all_sets:
          for file_set in file_sets:
              for fname in file_set[:2]:
                  raw_file = fname.split("/", 1)[0]
                  if raw_file not in RAW_FILES:
                      raise RuntimeError("Unknown raw file %s found in path %s" % (raw_file, fname))
                  raw_files.add(raw_file)
      return sorted(raw_files)
docs: Identify raw files that need to be downloaded for a given task.
  
      :param task: Sequence-to-sequence task.
      :param test_mode: Run in test mode, only downloading test data.
      :return: List of raw file names.