code: def on_before_reload(callback):
      """register a function to be called just before the server reloads."""
      add_callback(callback_map["callbacks_on_reload"], callback)
  
imports: import inspect
  import os
  from collections import namedtuple
  from typing import Optional, Any
  from fastapi import FastAPI
  from gradio import Blocks
  from modules import errors, timer
label_desc: Use image node_id 27 for calling a global function with example usage: on_before_reload(callback) without return types