fix error for checkpoint retrieval (#3)

- fix error for checkpoint retrieval (d7306367af057b51fac863af68d2c179d68d76b2)

app.py

@@ -43,7 +43,7 @@ def list_attributes_and_values():
     return html_script
 
 def retrieve_checkpoint():
-    return user['save_name']+".xlsx"
+    return users['save_name']
 
 with gr.Blocks() as demo:
     
@@ -54,7 +54,7 @@ with gr.Blocks() as demo:
             md_username = gr.Markdown(value='## Hi Guest!')
             btn_logout = gr.Button("Logout")
     with gr.Accordion(label="**Login** to keep user preferences", open=False):
-        st_user = gr.State(value={"name":"Guest", "hashed_password":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855", "history": { "keywords": [ "value1", "value3", "value4"], "prompts": [] }})
+        st_user = gr.State(value={"name":"Guest", "hashed_password":"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855", "history": { "keywords": [ "value1", "value3", "value4"], "prompts": [] }, "save_name" : "7783002652599471029.xlsx"})
         with gr.Column():
             tb_user = gr.Textbox(label='Username')
             tb_pwd = gr.Textbox(label='Password', type='password')