docs: private void writeObject(ObjectOutputStream out) throws IOException {
  		out.defaultWriteObject();
  		for (Field f : Variable.class.getDeclaredFields()) {
  			if (Modifier.isTransient(f.getModifiers())) {
  				try { backupForSerialization.put(new FieldOfObject(f), f.get(this)); }
  				catch (IllegalArgumentException e) { e.printStackTrace(); }
  				catch (IllegalAccessException e) { e.printStackTrace(); }
  			}
  		}
  	}