fix bug

app.py

@@ -85,11 +85,13 @@ def ovis_chat(chatbot, image_input):
     # debug
     print('*'*60)
     print('*'*60)
+    print('OVIS_CONV_START')
     for i, (request, answer) in enumerate(chatbot[:-1], 1):
         print(f'Q{i}:\n {request}')
         print(f'A{i}:\n {answer}')
     print('New_Q:\n', text_input)
     print('New_A:\n', response)
+    print('OVIS_CONV_END')
 
 def clear_chat():
     return [], None, ""