code: def add_one(self, x):
      return x + 1
  
imports: import unittest
  import parl
  import numpy
  from parl.remote.exceptions import FutureFunctionError
  from parl.remote.future_mode.future_object import FutureObject
  from parl.utils.test_utils import XparlTestCase
  import time
  import threading
  import random
label_desc: Use image node_id 2 for calling the Actor obj's underlying member method code with example usage: obj.add_one(x) and returns: unknown