code: def base_lc_types():
      import langchain.agents.agent
      import langchain.chains.base
      import langchain.schema
  
      return (
          langchain.chains.base.Chain,
          langchain.agents.agent.AgentExecutor,
          langchain.schema.BaseRetriever,
      )
  
imports: import json
  import logging
  import os
  import shutil
  import types
  from functools import lru_cache
  from importlib.util import find_spec
  from typing import Any, List, NamedTuple, Optional
  import cloudpickle
  import yaml
  from packaging import version
  import mlflow
  from mlflow.utils.class_utils import _get_class_from_string
label_desc: Use image node_id 1 for calling a global function with example usage: base_lc_types() and returns: langchain,  langchain,  langchain