Update app.py

app.py

@@ -4,6 +4,7 @@ import requests
 #tokenizer = AutoTokenizer.from_pretrained("liam168/c2-roberta-base-finetuned-dianping-chinese")
 conversation_history = ""
 def chat(input):
+    global conversation_history
     url = 'http://dark.21cnai.com:5000/api/chat'
     data = { "message": input }
     headers = {"Content-Type": "Application/json","Authorization":"Bearer kdfjwoieskdflasdnf"}