Is there any way to implement an option (let's say with name "option1") that it works like:

1. --option1 value1, means to set it to "value1"
2. --option1, means it's set without a value

Our application is a long running one that we'd like to persist a running checkpoint on disk if user wants to. If user indicates a file path, we write the checkpoint to it; If user just indicate the option to persist the checkpoint but doesn't specify a path, we write the checkpoint to the default path.

Is there any way we can do this?

Thanks
Emma