code: def tearDown(self) -> None:
      self.fl_server.stop()
  
imports: from multiprocessing import Process
  import unittest
  from uuid import uuid4
  import numpy
  import pandas
  import os
  import math
  from bigdl.ppml.fl import *
  from bigdl.ppml.fl.algorithms.fgboost_regression import FGBoostRegression
  from bigdl.ppml.fl.fl_server import FLServer
  from bigdl.ppml.fl.utils import init_fl_context
  from bigdl.ppml.fl.utils import FLTest
label_desc: Use image node_id 3 for calling the TestFGBoostRegression obj's underlying member method code with example usage: obj.tearDown() without return types