generator doesn't work on chatbot?

app.py

@@ -59,7 +59,8 @@ def evaluate(
                      token_stop = [0]) # stop generation whenever you see any token here
 
     instruction = re.sub(r'\n{2,}', '\n', instruction).strip().replace('\r\n','\n')
-    if input is not None:
+    use_input = (input is not None)
+    if use_input:
         input = re.sub(r'\n{2,}', '\n', input).strip().replace('\r\n','\n')
     ctx = generate_prompt(instruction, input, history) # pass the history to the generate_prompt function
     print(ctx + "\n")
@@ -88,7 +89,8 @@ def evaluate(
         tmp = pipeline.decode(all_tokens[out_last:])
         if '\ufffd' not in tmp:
             out_str += tmp
-            yield instruction, out_str.strip()
+            if use_input:
+                yield out_str.strip()
             out_last = i + 1
         if '\n\n' in out_str:
             break
@@ -96,8 +98,10 @@ def evaluate(
     del out
     del state
     gc.collect()
-    # yield out_str.strip()
-    yield instruction, out_str.strip()
+    if use_input:
+        yield out_str.strip()
+    else:
+        return instruction, out_str.strip()
 
 def user(message, chatbot):
     chatbot = chatbot or []
@@ -163,7 +167,7 @@ with gr.Blocks(title=title) as demo:
         with gr.Row():
             with gr.Column():
                 instruction = gr.Textbox(lines=2, label="Instruction", value='東京で訪れるべき素晴らしい場所とその紹介をいくつか挙げてください。')
-                input_instruct = gr.Textbox(lines=2, label="Input", placeholder="")
+                input_instruct = gr.Textbox(lines=2, label="Input", placeholder="", value="")
                 token_count_instruct = gr.Slider(10, 512, label="Max Tokens", step=10, value=333)
                 temperature_instruct = gr.Slider(0.2, 2.0, label="Temperature", step=0.1, value=1.2)
                 top_p_instruct = gr.Slider(0.0, 1.0, label="Top P", step=0.05, value=0.3)