code: def test_trimming_should_not_change_original_messages():
      messages = [
          {
              "role": "system",
              "content": "This is a short system message",
          },
          {
              "role": "user",
              "content": "This is a medium normal message, let's say litellm is awesome.",
          },
      ]
      messages_copy = copy.deepcopy(messages)
      trimmed_messages = trim_messages(
          messages, max_tokens=12, model="gpt-4-0613"
      )
      assert messages == messages_copy
  
imports: import sys, os
  from dotenv import load_dotenv
  import copy
  import os
  import pytest
  import litellm
  from litellm.utils import trim_messages, get_token_count, get_valid_models, check_valid_key, validate_environment, function_to_dict, token_counter
label_desc: Use image node_id 9 for calling a global function with example usage: test_trimming_should_not_change_original_messages() without return types