langchain/agents/react/base.py/ReActChain/__init__
class ReActChain:    def __init__(self, llm: BaseLanguageModel, docstore: Docstore, **kwargs: Any):
        """Initialize with the LLM and a docstore."""
        docstore_explorer = DocstoreExplorer(docstore)
        tools = [
            Tool(
                name="Search",
                func=docstore_explorer.search,
                description="Search for a term in the docstore.",
            ),
            Tool(
                name="Lookup",
                func=docstore_explorer.lookup,
                description="Lookup a term in the docstore.",
            ),
        ]
        agent = ReActDocstoreAgent.from_llm_and_tools(llm, tools)
        super().__init__(agent=agent, tools=tools, **kwargs)