code: def fetch_impl(self, request, callback):
      self._requests.append((request, callback))
      self._process_queue()
      self._set_timeout(0)
  
imports: from __future__ import absolute_import, division, print_function
  import collections
  import functools
  import logging
  import pycurl
  import threading
  import time
  from io import BytesIO
  from tornado import httputil
  from tornado import ioloop
  from tornado import stack_context
  from tornado.escape import utf8, native_str
  from tornado.httpclient import HTTPResponse, HTTPError, AsyncHTTPClient, main
label_desc: Use image node_id 3 for calling the CurlAsyncHTTPClient obj's underlying member method code with example usage: obj.fetch_impl(request, callback) without return types