* @return String
   */
  public static String fileNameAsDirectory(String file) {
    { char separator = Stella.directorySeparatorForFile(file);
      int last = file.length() - 1;

      if ((last < 0) ||
          (file.charAt(last) == separator)) {
        return (file);
      }
      else {
        return (file + Native.makeString(1, separator));
      }
    }
  }