code: def __init__(self, client_num=None):
      self.server = grpc.server(
          futures.ThreadPoolExecutor(max_workers=5)
      )
      self.port = 8980
      self.client_num = client_num
      self.secure = False
      self.load_config()
      # a chance to overwrite client num
      if client_num is not None:
          self.conf["clientNum"] = client_num
  
file_path: BigDL/python/ppml/src/bigdl/ppml/fl/nn/fl_server.py
imports: from concurrent import futures
  import grpc
  from bigdl.ppml.fl import *
  from bigdl.ppml.fl.nn.nn_service import NNServiceImpl
  import yaml
  import click
  from bigdl.ppml.fl.psi.psi_service import PSIServiceImpl
  from bigdl.ppml.fl.nn.generated.nn_service_pb2_grpc import *
  from bigdl.ppml.fl.nn.generated.psi_service_pb2_grpc import *
label_desc: Use image node_id 1 to create a new FLServer object from inherited base classes: object with example: obj = FLServer(client_num)