change default to gpt4 and fix object ref possible bug

app.py

@@ -2,27 +2,26 @@ import gradio as gr
 import openai
 
 
-def get_answer_chatgpt(chat_history, message, system_message=None, model="gpt-3.5-turbo", max_length=1000):
+def get_answer_chatgpt(chat_history, message, system_message=None, model="gpt-4", max_length=1000):
     messages = []
     if model is None:
-        model = "gpt-3.5-turbo"
+        model = "gpt-4"
 
     if system_message or system_message != "":
         TEMPLATE_SYSTEM = {"role": "system", "content": system_message}
         messages.append(TEMPLATE_SYSTEM)
 
-    TEMPLATE_USER = {"role": "user"}
-    TEMPLATE_BOT = {"role": "assistant"}
-
     # add historical conversation
     for pair in chat_history:
-        TEMPLATE_USER["content"] = pair[0]
-        TEMPLATE_BOT["content"] = pair[1]
+        TEMPLATE_USER = {"role": "user", "content": pair[0]}
+        TEMPLATE_BOT = {"role": "assistant", "content": pair[1]}
         messages.append(TEMPLATE_USER)
         messages.append(TEMPLATE_BOT)
+
     # add latest input
     TEMPLATE_USER["content"] = message
     messages.append(TEMPLATE_USER)
+
     response = openai.ChatCompletion.create(
         model=model,
         messages=messages,
@@ -46,7 +45,7 @@ with gr.Blocks() as demo:
             clear = gr.Button("Clear all converstation")
         with gr.Column(scale=5):
             with gr.Accordion("Parameters", open=False):
-                model = gr.Dropdown(["gpt-3.5-turbo", "gpt-4"], label="Model", value="gpt-3.5-turbo")
+                model = gr.Dropdown(["gpt-4", "gpt-3.5-turbo"], label="Model", value="gpt-4")
                 max_length = gr.Slider(0, 10000, value=1000, step=1, label="Maximum length token", interactive=True)
 
     system_message = gr.Textbox(placeholder="You are helpful assistence", lines=5, label="System Message")