add os.

app.py

@@ -1,13 +1,20 @@
 import gradio as gr
 import random
+import os
 from huggingface_hub import InferenceClient
 
+client = InferenceClient(
+    model="Qwen/Qwen2.5-7B-Instruct",
+    token=os.getenv("HF_TOKEN")
+)
+
 client=InferenceClient("Qwen/Qwen2.5-7B-Instruct")
 
 def respond(message, history):
     messages=[{"role": "system", "content": "You're a friendly chatbot!"}]
     
-
+    if history:
+    messages.extend(history)
 
     messages.append({"role": "user", "content": message})