saveName()

NameRepository.kt

override fun saveName(name: String): Completable = prefSubject
                    .firstOrError()
                    .editSharedPreferences {
                        putString(KEY_NAME, name)
                    }

    fun Single<SharedPreferences>.editSharedPreferences(batch: SharedPreferences.Editor.() -> Unit): Completable =
            flatMapCompletable {
                Completable.fromAction {
                    it.edit().also(batch).apply()
                }
            }