Fix unique session id

app.py

@@ -16,7 +16,9 @@ from vectara_agent.agent import AgentStatusType
 from agent import initialize_agent, get_agent_config
 
 # Setup for HTTP API Call to Amplitude Analytics
-device_id = str(uuid.uuid4())
+if 'device_id' not in locals():
+    device_id = str(uuid.uuid4())
+
 headers = {
     'Content-Type': 'application/json',
     'Accept': '*/*'
@@ -118,7 +120,7 @@ def launch_bot():
                 "event_properties": {
                     "query": prompt,
                     "Space Name": "ev-assistant"
-                    }
+                }
             }]
         }