langchain/callbacks/tracers/langchain_v1.py/LangChainTracerV1/_load_session
class LangChainTracerV1:    def _load_session(self, session_name: Optional[str] = None) -> TracerSessionV1:
        """Load a session from the tracer."""
        try:
            url = f"{self._endpoint}/sessions"
            if session_name:
                url += f"?name={session_name}"
            r = requests.get(url, headers=self._headers)

            tracer_session = TracerSessionV1(**r.json()[0])
        except Exception as e:
            session_type = "default" if not session_name else session_name
            logging.warning(
                f"Failed to load {session_type} session, using empty session: {e}"
            )
            tracer_session = TracerSessionV1(id=1)

        self.session = tracer_session
        return tracer_session