code: def test_to_dict_with_lambda_streaming_callback(self):
      component = OpenAIGenerator(
          api_key="test-api-key",
          model="gpt-4",
          streaming_callback=lambda x: x,
          api_base_url="test-base-url",
          generation_kwargs={
              "max_tokens": 10,
              "some_test_param": "test-params",
          },
      )
      data = component.to_dict()
      assert data == {
          "type": "haystack.components.generators.openai.OpenAIGenerator",
          "init_parameters": {
              "model": "gpt-4",
              "system_prompt": None,
              "api_base_url": "test-base-url",
              "streaming_callback": "test_openai.<lambda>",
              "generation_kwargs": {
                  "max_tokens": 10,
                  "some_test_param": "test-params",
              },
          },
      }
  
imports: import os
  from typing import List
  import pytest
  from openai import OpenAIError
  from haystack.components.generators import OpenAIGenerator
  from haystack.components.generators.utils import default_streaming_callback
  from haystack.dataclasses import StreamingChunk, ChatMessage
label_desc: Use image node_id 6 for calling the TestOpenAIGenerator obj's underlying member method code with example usage: obj.test_to_dict_with_lambda_streaming_callback() without return types