@Override
  public @Nullable Boolean contains(@NotNull String word) {
    if (dictionaries == null) {
      // still ("WORD_OF_ENTIRELY_UNKNOWN_LETTERS_FOR_ALL");
      return null;
    }

    int errors = 0;
    for (Dictionary dictionary : dictionaries) {
      Boolean contains = dictionary.contains(word);
      if (contains == null) {
        errors++;
      }
      else if (contains) {
        return true;
      }
    }

    //("WORD_OF_ENTIRELY_UNKNOWN_LETTERS_FOR_ALL");
    if (errors == dictionaries.size()) {
      return null;
    }
    return false;
  }
@Override
  public @Nullable Boolean contains(@NotNull String word)