code: public static void writeVocabCache(@NonNull VocabCache<VocabWord> vocabCache, @NonNull File file)
              throws IOException {
          try (FileOutputStream fos = new FileOutputStream(file)) {
              writeVocabCache(vocabCache, fos);
          }
      }
docs: This method saves vocab cache to provided File.
  Please note: it saves only vocab content, so it's suitable mostly for BagOfWords/TF-IDF vectorizers
  
  @param vocabCache
  @param file
  @throws UnsupportedEncodingException