langchain/agents/react/base.py/DocstoreExplorer/search
class DocstoreExplorer:    def search(self, term: str) -> str:
        """Search for a term in the docstore, and if found save."""
        result = self.docstore.search(term)
        if isinstance(result, Document):
            self.document = result
            return self._summary
        else:
            self.document = None
            return result