I was hoping to make it similar to the `subscribeW...

# rx

[thomasnield]

I was hoping to make it similar to the subscribeWith() but unfortunately there is no way to infer the generics using mutable builders. Should I go ahead and start working on a PR using the argument style above? Or do you all feel this might not be worth the effort? Should we be concerned it is not consistent style-wise with the subscribeWith()?