Proposed change of Docs: prevent overwriting Long Running Function Tool

### What part of the docs needs improvement?
https://google.github.io/adk-docs/tools/function-tools/#intermediate-final-result-updates

in the sample python code
---

### Current text / code

```python
long_running_function_call, long_running_function_response, ticket_id = None, None, None
async for event in events_async:
if not long_running_function_call:
long_running_function_call = get_long_running_function_call(event)
else:
long_running_function_response = get_function_response(
event, long_running_function_call.id
)
if long_running_function_response:
ticket_id = long_running_function_response.response['ticket-id']
```

---

###  Proposed change

```diff
if not long_running_function_call:
long_running_function_call = get_long_running_function_call(event)
- else:
+ elif not long_running_function_response:
```

---
Only attempt to capture the FunctionResponse once; subsequent events may be plain chat messages.

### Why
Some LLM backends (e.g. qwen‑plus in my case) emit an additional text event for user‑visible chat message after they got the FunctionResponse.
The current else: branch runs on that extra event, get_function_response() returns None, and the variable is unintentionally reset. As a result, the if long_running_function_response: block never triggers and the sample stops before forwarding the final status.

Guarding with elif not long_running_function_response keeps the original FunctionResponse intact and makes the example behave correctly across different model streams, reducing confusion for newcomers.

Thanks for considering!