docs: private void checkFileValidity(File image) throws TwitterException {
          if (!image.exists()) {
              //noinspection ThrowableInstanceNeverThrown
              throw new TwitterException(new FileNotFoundException(image + " is not found."));
          }
          if (!image.isFile()) {
              //noinspection ThrowableInstanceNeverThrown
              throw new TwitterException(new IOException(image + " is not a file."));
          }
      }