Update assistant_api.py

assistant_api.py

@@ -39,7 +39,7 @@ class  MathTutor:
     messages = self.client.beta.threads.messages.list(thread_id=self.thread.id)
     last_message = messages.data
     my_text = []
-    for i in range(len(last_message)):
+    for i in range(0,len(last_message)-1):
       last_message = messages.data[i]
       text = last_message.content[0].text.value
       my_text.append(text)