code: def get_server_url(self):
      assert self.socket_created_future.result(self.spinup_timeout)
      return "http://%s:%s" % (self.server_host, self.server_port)
  
imports: import base64
  import http.server
  import select
  import socket
  import socketserver
  import threading
  from urllib.request import urlopen
label_desc: Use image node_id 4 for calling the HttpServerThread obj's underlying member method code with example usage: obj.get_server_url() and returns: unknown