class_docstr: Class to wrap Langchain LLMs and make PandasAI interoperable
  with LangChain.
code: def call(self, instruction: AbstractPrompt, suffix: str = "") -> str:
      prompt = instruction.to_string() + suffix
      return self._langchain_llm.predict(prompt)
  
imports: from pandasai.prompts.base import AbstractPrompt
  from .base import LLM
label_desc: Use image node_id 2 for calling the LangchainLLM obj's underlying member method code with example usage: obj.call(instruction, suffix) and returns: self