protected val <T> StateCommand<T>.consumer: Consumer<T> get() = relay

    inner class StateCommand<T>(
            isIdle: Observable<Boolean>? = null
    ) {
        internal val relay = PublishRelay.create<T>().toSerialized()

        var bufferedValue: T? = null
            private set

        private val bufferSize = 1

        val observable =
                (if (isIdle == null) {
                    relay.bufferWhileUnbind(bufferSize)
                } else {
                    relay.bufferWhileIdle(isIdle, bufferSize)
                })
                        .doOnNext { bufferedValue = it }
                        .publish()
                        .apply { connect() }
    }