Ensure the `"Observation:"` tag is present after stopping, since stopping on that token prevents it from appearing in the output.

unit1/dummy_agent_library.ipynb

@@ -449,7 +449,7 @@
         "messages=[\n",
         "    {\"role\": \"system\", \"content\": SYSTEM_PROMPT},\n",
         "    {\"role\": \"user\", \"content\": \"What's the weather in London ?\"},\n",
-        "    {\"role\": \"assistant\", \"content\": output.choices[0].message.content+get_weather('London')},\n",
+        "    {\"role\": \"assistant\", \"content\": output.choices[0].message.content+"Observation:\n"+get_weather('London')},\n",
         "]\n",
         "messages"
       ]