class_docstr: The set of expected inputs to a custom handler for a
code: def log_success_event(
      self, kwargs, response_obj, start_time, end_time
  ):
      try:
          self.states.append("sync_success")
          ## START TIME
          assert isinstance(start_time, datetime)
          ## END TIME
          assert isinstance(end_time, datetime)
          ## RESPONSE OBJECT
          assert isinstance(response_obj, litellm.ModelResponse)
          ## KWARGS
          assert isinstance(kwargs["model"], str)
          assert isinstance(kwargs["messages"], list) and isinstance(
              kwargs["messages"][0], dict
          )
          assert isinstance(kwargs["optional_params"], dict)
          assert isinstance(kwargs["litellm_params"], dict)
          assert isinstance(
              kwargs["start_time"], (datetime, type(None))
          )
          assert isinstance(kwargs["stream"], bool)
          assert isinstance(kwargs["user"], (str, type(None)))
          assert (
              isinstance(kwargs["input"], list)
              and isinstance(kwargs["input"][0], dict)
          ) or isinstance(kwargs["input"], (dict, str))
          assert isinstance(kwargs["api_key"], (str, type(None)))
          assert isinstance(
              kwargs["original_response"],
              (str, litellm.CustomStreamWrapper),
          )
          assert isinstance(
              kwargs["additional_args"], (dict, type(None))
          )
          assert isinstance(kwargs["log_event_type"], str)
          assert kwargs["cache_hit"] is None or isinstance(
              kwargs["cache_hit"], bool
          )
      except:
          print(f"Assertion Error: {traceback.format_exc()}")
          self.errors.append(traceback.format_exc())
  
file_path: litellm/litellm/tests/test_custom_callback_router.py
imports: import sys, os, time, inspect, asyncio, traceback
  from datetime import datetime
  import pytest
  from typing import Optional, Literal, List
  from litellm import Router, Cache
  import litellm
  from litellm.integrations.custom_logger import CustomLogger
label_desc: Use image node_id 4 for calling the CompletionCustomHandler obj's underlying member method code with example usage: obj.log_success_event(kwargs, response_obj, start_time, end_time) without return types