java - Call void method and pass trought arguments RxJava -

i'm looking better :

mrestservice.login(email, password) // login user in                 .flatmap(user -> observable.zip(                         mrestservice.start(user._token), // start session                         observable.just(user),                         (v, u) -> (user) u // pass user throught                 ))                 .subscribe(user -> {                 }, throwable -> {                                      }); 

but coudn't come better.

the start method on mrestservice perform side effect. can use doonnext method here sort of side effect.

 mrerstservice.login(email, password)               .doonnext(u -> mrestservice.start(user._token))               .subscribe();