langchain/tools/gmail/search.py/GmailSearch/_parse_threads
class GmailSearch:    def _parse_threads(self, threads: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
        # Add the thread message snippets to the thread results
        results = []
        for thread in threads:
            thread_id = thread["id"]
            thread_data = (
                self.api_resource.users()
                .threads()
                .get(userId="me", id=thread_id)
                .execute()
            )
            messages = thread_data["messages"]
            thread["messages"] = []
            for message in messages:
                snippet = message["snippet"]
                thread["messages"].append({"snippet": snippet, "id": message["id"]})
            results.append(thread)

        return results