Update app.py

app.py

@@ -35,7 +35,7 @@ def answer(history, sample=True, top_p=1, temperature=0.7):
     preprocess_history = []
 
     for i in range(len(history)):
-        preprocess_history[i] = preprocess(text)
+        preprocess_history.append(preprocess(text))
     
     #text = preprocess(text)
     #print('用户: '+text)