Update app.py

app.py

@@ -59,7 +59,7 @@ See https://github.com/openai/openai-python/blob/main/chatml.md for information
 
 def forget_long_term(messages, max_num_tokens=500):
     while num_tokens_from_messages(messages)>max_num_tokens:
-        if messages[0]["role"]=="system" and not len(messages[0]["content"]>=max_num_tokens):
+        if messages[0]["role"]=="system" and not len(messages[0]["content"])>=max_num_tokens:
             messages = messages[:1] + messages[2:]
         else:
             messages = messages[1:]