class_docstr: HttpServer
  
  Flask HTTP server. Defines two routes, `/parameters` to GET current
  parameters held by this server, and `/update` which can be used to
  POST updates.
class_docstr_tok: ["HttpServer","Flask","HTTP","server",".","Defines","two","routes",",","`","\/parameters","`","to","GET","current","parameters","held","by","this","server",",","and","`","\/update","`","which","can","be","used","to","POST","updates","."]
code: def stop(self):
      self.server.terminate()
      self.server.join()
  
imports: import abc
  import pickle
  import socket
  from threading import Thread
  from flask import Flask, request
  from multiprocessing import Process
  from tensorflow.keras.models import Model
  from elephas.utils.sockets import determine_master
  from elephas.utils.sockets import receive, send
  from elephas.utils.serialization import dict_to_model
  from elephas.utils.rwlock import RWLock
  from elephas.utils.notebook_utils import is_running_in_notebook
  from elephas.utils import subtract_params
label_desc: Use image node_id 3 for calling the HttpServer obj's underlying member method code with example usage: obj.stop() without return types