code: def tearDown(self) -> None:
      self.fl_server.stop()
  
file_path: BigDL/python/ppml/test/bigdl/ppml/fl/psi/test_psi.py
imports: import unittest
  from bigdl.ppml.fl.psi.psi_client import PSI
  from bigdl.ppml.fl.nn.fl_server import FLServer
  from bigdl.ppml.fl.nn.fl_context import init_fl_context
  from bigdl.ppml.fl.utils import FLTest
label_desc: Use image node_id 2 for calling the TestPSI obj's underlying member method code with example usage: obj.tearDown() without return types