langchain/callbacks/tracers/langchain_v1.py/LangChainTracerV1/__init__
class LangChainTracerV1:    def __init__(self, **kwargs: Any) -> None:
        """Initialize the LangChain tracer."""
        super().__init__(**kwargs)
        self.session: Optional[TracerSessionV1] = None
        self._endpoint = _get_endpoint()
        self._headers = get_headers()