code: def _get_server_address_if_manually_set() -> Optional[str]:
      if config.is_manually_set("browser.serverAddress"):
          return url_util.get_hostname(
              config.get_option("browser.serverAddress")
          )
      return None
  
file_path: streamlit/lib/streamlit/web/server/server_util.py
imports: from typing import Optional
  from urllib.parse import urljoin
  import tornado.web
  from streamlit import config, net_util, url_util
label_desc: Use image node_id 2 for calling a global function with example usage: _get_server_address_if_manually_set() and returns: None, url_util