anchor.diff:      if (!FileSystemEntity.isDirectorySync('$sdkPath/lib')) {
         print("'$sdkPath/lib' does not exist.");
         _printUsage();
  +      exitCode = 1;
         return;
       }
     } else {
  
positive.code:   if (FileSystemEntity.isDirectorySync(outputFilePath)) {
      print("'$outputFilePath' is a directory.");
      _printUsage();
      return;
    }
    //
  
negative.code: main(List<String> args) {
    if (args.length < 1 || args.length > 2) {
      _printUsage();
      exitCode = 1;
      return;
    }
    //
  