diff --git a/comps/llms/src/doc-summarization/integrations/common.py b/comps/llms/src/doc-summarization/integrations/common.py
index 934c80072..b989cf4e9 100644
--- a/comps/llms/src/doc-summarization/integrations/common.py
+++ b/comps/llms/src/doc-summarization/integrations/common.py
@@ -191,8 +191,11 @@ async def generate(self, input: DocSumChatCompletionRequest, client):
         if input.stream:
 
             import json
+
             from langserve.serialization import WellKnownLCSerializer
+
             _serializer = WellKnownLCSerializer()
+
             def extract_llm_tokens(stream_output):
                 op_data = _serializer.dumps({"ops": stream_output.ops}).decode("utf-8")
                 logger.info(op_data)
@@ -211,7 +214,7 @@ async def stream_generator():
 
                     if logflag:
                         logger.info(data)
-                    if data != '':
+                    if data != "":
                         yield f"data: {data}\n\n"
                 yield "data: [DONE]\n\n"