private void writeObject(ObjectOutputStream out) throws IOException {
   out.writeInt(CURRENT_SERIAL_VERSION);
   out.writeObject(prefix);
   out.writeInt(gramSizes.length);
   for (int i = 0; i < gramSizes.length; i++) out.writeInt(gramSizes[i]);
   out.writeBoolean(distinguishBorders);
 }
 private void writeObject(ObjectOutputStream out) throws IOException {
   out.writeInt(CURRENT_SERIAL_VERSION);
 }