anchor.diff:  /// The file name of a path.
   ///
   /// The file name is everything after the last occurrence of
  -/// [Platform.pathSeparator].
  +/// [Platform.pathSeparator], or the entire string if no
  +/// path separator occurs in the string.
   String fileName(String path) {
     var separator = Platform.pathSeparator;
     int lastSeparator = path.lastIndexOf(separator);
  
positive.code: }
  
  /// Join path parts with the [Platform.pathSeparator].
  String pathJoin(String part1, String part2, [String part3]) {
    var separator = Platform.pathSeparator;
    if (part3 == null) {
      return "$part1$separator$part2";
    }
    return "$part1$separator$part2$separator$part3";
  }
  
  /// Join an unknown number of path parts with [Platform.pathSeparator].
  String pathJoinAll(Iterable<String> parts) =>
      parts.join(Platform.pathSeparator);
  
  // Character constants used by this package.
  /// "Line feed" control character.
  
negative.code:   return path.substring(lastSeparator + separator.length);
  }
  
  /// The directory name of a path.
  ///
  /// The directory name is everything before the last occurrence of
  /// [Platform.pathSeparator], or the empty string if no
  /// path separator occurs in the string.
  String dirName(String path) {
    var separator = Platform.pathSeparator;
    int lastSeparator = path.lastIndexOf(separator);
  