Map.java

getUserObservable()
    .map(new Function<ApiUser, User>() {
        @Override
        public User apply(ApiUser apiUser) throws Exception {
          // here we get the ApiUser from the server
            User user = new User(apiUser);
            // then by converting it into the user, we are returning
            return user;
        }
    })
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(getObserver());