docstr: Test accessing with a client with start_server=StartServer.DONT_START to an external unavailable server 
docstr_tok: ["Test","accessing","with","a","client","with","start_server=StartServer.DONT_START","to","an","external","unavailable","server"]
code: def test_external_server_unavailable(self):
      """Test accessing with a client with start_server=StartServer.DONT_START to an external unavailable server"""
      with pytest.raises(corenlp.AnnotationException):
          with corenlp.CoreNLPClient(
              start_server=corenlp.StartServer.DONT_START,
              endpoint="http://localhost:9001",
          ) as external_server_client:
              ann = external_server_client.annotate(
                  TEXT,
                  annotators="tokenize,ssplit,pos",
                  output_format="text",
              )
  
imports: from http.server import BaseHTTPRequestHandler, HTTPServer
  import multiprocessing
  import pytest
  import requests
  import stanza.server
  import stanza.server.client
  import shlex
  import subprocess
  import time
  from stanza.models.constituency import tree_reader
  from stanza.tests import *
label_desc: Use image node_id 14 for calling the TestCoreNLPClient obj's underlying member method code with example usage: obj.test_external_server_unavailable() without return types