code: def log_success_event(
      self, kwargs, response_obj, start_time, end_time
  ):
      print(f"On Success")
      assert kwargs["user"] == "proxy-user"
      assert kwargs["model"] == "gpt-3.5-turbo"
      assert kwargs["max_tokens"] == 10
  
imports: import sys, os
  import traceback
  from dotenv import load_dotenv
  import os, io
  import pytest, logging, asyncio
  import litellm
  from litellm import embedding, completion, completion_cost, Timeout
  from litellm import RateLimitError
  from fastapi.testclient import TestClient
  from fastapi import FastAPI
  from litellm.proxy.proxy_server import router, save_worker_config, initialize
  from litellm.integrations.custom_logger import CustomLogger
  from litellm.proxy.proxy_server import ProxyConfig
label_desc: Use image node_id 2 for calling the MyCustomHandler obj's underlying member method code with example usage: obj.log_success_event(kwargs, response_obj, start_time, end_time) without return types