Update app.py

app.py

@@ -27,13 +27,13 @@ from collections import defaultdict, OrderedDict
 from langchain_community.vectorstores import FAISS
 from langchain_community.embeddings import HuggingFaceEmbeddings
 from sentence_transformers import SentenceTransformer
-# from langchain.retrievers import BM25Retriever
-from langchain_community.retrievers import BM25Retriever
-# from langchain.schema import Document
+from langchain.retrievers import BM25Retriever
+# from langchain_community.retrievers import BM25Retriever
+from langchain.schema import Document
 # from langchain_core.schema import Document
-from langchain_core.documents import Document
-# from langchain_core.tools import tool
-from langchain_core.tools import StructuredTool
+# from langchain_core.documents import Document
+from langchain_core.tools import tool
+# from langchain_core.tools import StructuredTool
 
 # =======================================================================
 # 2. 初始設定與資料庫載入