from langchain_core.language_models.llms import LLM
from langchain_core.callbacks.manager import CallbackManagerForLLMRun
from typing import Any, List, Optional

class FakeLLM(LLM):
    """
    An LLM class that returns nothing of value and is a temp class designed to work in Langchain.
    """
    def _call(
        self,
        prompt: str,
        stop: Optional[List[str]] = None,
        run_manager: Optional[CallbackManagerForLLMRun] = None,
        **kwargs: Any,
    ) -> str:
        if stop is not None:
            raise ValueError("stop kwargs are not permitted.")
        return prompt

    @property
    def _llm_type(self) -> str:
        """Get the type of language model used by this chat model. Used for logging purposes only."""
        return "custom"