The code changes in `sub.go` update the handling of NATS subscriptions. The `Subscribe` function now takes in a `config` parameter, allowing for more flexibility in configuring the subscription. Additionally, the `Subscribe` function now uses the `handler` and `marshaler` parameters to handle incoming messages and marshal/unmarshal data, respectively. These changes improve the modularity and extensibility of the code when working with NATS subscriptions.
windyboy