anchor.diff:  class ErrorFormatter {
     static final int _pipeCodeUnit = '|'.codeUnitAt(0);
     static final int _slashCodeUnit = '\\'.codeUnitAt(0);
  +  static final int _newline = '\n'.codeUnitAt(0);
  +  static final int _return = '\r'.codeUnitAt(0);
   
     final StringSink out;
     final CommandLineOptions options;
  
positive.code:       out.write('|');
        out.write(length);
        out.write('|');
        out.write(escapePipe(error.message));
        out.writeln();
      } else {
        // Get display name.
  
negative.code:     }
    }
  
    static String escapeForMachineMode(String input) {
      StringBuffer result = new StringBuffer();
      for (int c in input.codeUnits) {
        if (c == _newline) {
          result.write(r'\n');
        } else if (c == _return) {
          result.write(r'\r');
        } else {
          if (c == _slashCodeUnit || c == _pipeCodeUnit) {
            result.write('\\');
          }
          result.writeCharCode(c);
        }
      }
      return result.toString();
    }
  