langchain/callbacks/streamlit.py/StreamlitCallbackHandler/on_agent_finish
class StreamlitCallbackHandler:    def on_agent_finish(self, finish: AgentFinish, **kwargs: Any) -> None:
        """Run on agent end."""
        # st.write requires two spaces before a newline to render it
        st.write(finish.log.replace("\n", "  \n"))