diff --git a/server/knowledge_base/migrate.py b/server/knowledge_base/migrate.py
index 58a2ffd..146dc77 100644
--- a/server/knowledge_base/migrate.py
+++ b/server/knowledge_base/migrate.py
@@ -1,9 +1,13 @@
-from configs import (EMBEDDING_MODEL, DEFAULT_VS_TYPE, ZH_TITLE_ENHANCE,
-                     CHUNK_SIZE, OVERLAP_SIZE,
-                    logger, log_verbose)
-from server.knowledge_base.utils import (get_file_path, list_kbs_from_folder,
-                                        list_files_from_folder,files2docs_in_thread,
-                                        KnowledgeFile,)
+from configs import (
+    EMBEDDING_MODEL, DEFAULT_VS_TYPE, ZH_TITLE_ENHANCE,
+    CHUNK_SIZE, OVERLAP_SIZE,
+    logger, log_verbose
+)
+from server.knowledge_base.utils import (
+    get_file_path, list_kbs_from_folder,
+    list_files_from_folder, files2docs_in_thread,
+    KnowledgeFile
+)
 from server.knowledge_base.kb_service.base import KBServiceFactory
 from server.db.models.chat_history_model import ChatHistoryModel
 from server.db.repository.knowledge_file_repository import add_file_to_db # ensure Models are imported
@@ -24,15 +28,15 @@ def reset_tables():
 
 
 def import_from_db(
-    sqlite_path: str = None,
-    # csv_path: str = None,
+        sqlite_path: str = None,
+        # csv_path: str = None,
 ) -> bool:
-    '''
+    """
     在知识库与向量库无变化的情况下，从备份数据库中导入数据到 info.db。
     适用于版本升级时，info.db 结构变化，但无需重新向量化的情况。
     请确保两边数据库表名一致，需要导入的字段名一致
     当前仅支持 sqlite
-    '''
+    """
     import sqlite3 as sql
     from pprint import pprint
 
@@ -76,22 +80,23 @@ def file_to_kbfile(kb_name: str, files: List[str]) -> List[KnowledgeFile]:
 
 
 def folder2db(
-    kb_names: List[str],
-    mode: Literal["recreate_vs", "update_in_db", "increament"],
-    vs_type: Literal["faiss", "milvus", "pg", "chromadb"] = DEFAULT_VS_TYPE,
-    embed_model: str = EMBEDDING_MODEL,
-    chunk_size: int = CHUNK_SIZE,
-    chunk_overlap: int = OVERLAP_SIZE,
-    zh_title_enhance: bool = ZH_TITLE_ENHANCE,
+        kb_names: List[str],
+        mode: Literal["recreate_vs", "update_in_db", "increament"],
+        vs_type: Literal["faiss", "milvus", "pg", "chromadb"] = DEFAULT_VS_TYPE,
+        embed_model: str = EMBEDDING_MODEL,
+        chunk_size: int = CHUNK_SIZE,
+        chunk_overlap: int = OVERLAP_SIZE,
+        zh_title_enhance: bool = ZH_TITLE_ENHANCE,
 ):
-    '''
+    """
     use existed files in local folder to populate database and/or vector store.
     set parameter `mode` to:
         recreate_vs: recreate all vector store and fill info to database using existed files in local folder
         fill_info_only(disabled): do not create vector store, fill info to db using existed files only
         update_in_db: update vector store and database info using local files that existed in database only
         increament: create vector store and database info for local files that not existed in database only
-    '''
+    """
+
     def files2vs(kb_name: str, kb_files: List[KnowledgeFile]):
         for success, result in files2docs_in_thread(kb_files,
                                                     chunk_size=chunk_size,
@@ -146,10 +151,10 @@ def folder2db(
 
 
 def prune_db_docs(kb_names: List[str]):
-    '''
+    """
     delete docs in database that not existed in local folder.
     it is used to delete database docs after user deleted some doc files in file browser
-    '''
+    """
     for kb_name in kb_names:
         kb = KBServiceFactory.get_service_by_name(kb_name)
         if kb and kb.exists():
@@ -164,10 +169,10 @@ def prune_db_docs(kb_names: List[str]):
 
 
 def prune_folder_files(kb_names: List[str]):
-    '''
+    """
     delete doc files in local folder that not existed in database.
-    is is used to free local disk space by delete unused doc files.
-    '''
+    it is used to free local disk space by delete unused doc files.
+    """
     for kb_name in kb_names:
         kb = KBServiceFactory.get_service_by_name(kb_name)
         if kb and kb.exists():