How can I get the coversation history in workflow?

I have two agents: Coder and Reviewer

```
Flow(agent_network=network, router=router)
        .auto_route('help me to write code about XXX')             # route to Coder
        .auto_route('is the answer correct?')                      # route to Reviewer
```

how can the Reviewer agent get the answer from Coder agent in `handle_task` method?