docs: public static void main(String[] args) {
          if (args.length != 2) {
              System.err.println("Please specify dir or filename | output file location");
              return;
          }
  
          StopwordsGenerator stopwordsGenerator = new StopwordsGenerator();
  
          File file = new File(args[0]);
  
          if (file.isFile()) {
              WikiSingleWordCount.generateFromFile(file, stopwordsGenerator);
          } else {
              File[] files = file.listFiles();
              Arrays.stream(files).parallel()
                      .filter(File::isFile)
                      .forEach(f -> WikiSingleWordCount.generateFromFile(f, stopwordsGenerator));
          }
  
          stopwordsGenerator.normalize();
          List<Map.Entry<String, Double>> result = stopwordsGenerator.getProbability()
                  .entrySet().stream()
                  .sorted((o1, o2) -> o2.getValue().compareTo(o1.getValue()))
                  .collect(Collectors.toList());
          stopwordsGenerator.writeFile(args[1], result);
      }