docs: public <O> O get(Class<O> clazz, String key){
  //        canWrite(); TODO disabled for now
          Object o = null;
          try{
              o = user_data.get(key);
              return clazz.cast( o );
          } catch (Exception e){
              e.printStackTrace();
              System.out.println("Get(" + clazz.getSimpleName() + "," + key + ")");
              System.out.println(o);
              return null;
          }
      }