code: def _create_http_client():
      
      global _http_client
  
      defaults = {'user_agent': USER_AGENT}
      auth_username, auth_password = _credentials
      if auth_username and auth_password:
          defaults['auth_username'] = auth_username
          defaults['auth_password'] = auth_password
  
      _http_client = httpclient.AsyncHTTPClient(
          force_instance=True, defaults=defaults,
          max_clients=_max_clients)
docs: Create the HTTP client with authentication credentials if required.