code: def stop_servers(self):
      for server in self._servers.values():
          if server.running:
              log.debug("stopping TensorBoard server (%s)", server)
              server.stop()
  
imports: import json
  import logging
  import math
  import os
  import socket
  import subprocess
  import sys
  import threading
  import time
  from werkzeug.exceptions import NotFound
  from werkzeug.utils import redirect
  from guild import serving_util
  from guild import util
  from guild import var
label_desc: Use image node_id 7 for calling the TBServers obj's underlying member method code with example usage: obj.stop_servers() without return types