code: def before_req_hook():
      """A custom before request handler.
  
      Can implement things such as authentication, special handling, etc.
      """
      if not is_logged_in():
          app_logger.warning("Hello from before request!")
          return "Unauthorized", 403
  
imports: import logging
  from mlflow.server import app
label_desc: Use image node_id 2 for calling a global function with example usage: before_req_hook() and returns: str,  int