api.authUser(login, password)
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe({
               //success
			   saveUser()
            }, {
				//error
                api.createUser(..)
                    .subscribeOn(Schedulers.io())
                    .observeOn(AndroidSchedulers.mainThread())
					...
            })