redis event playback

      end

    end

    if query.since != :now

      # playback

      q_until = query.until.is_a?(Symbol)? Time.now.to_i : query.until 

      puts "zrangebyscore #{@prefix} #{query.since} #{q_until}"

      @redis.zrangebyscore(@prefix, query.since, q_until) do |res|

        res.each do |event|

          block.call(event) if query.matches?(event)

        end

        if query.until != :stream

        # call on_finish

          on_finish

        end

      end

    end

  end

  def on_finish(&block)    

    return @on_finish = block if block_given?

    @on_finish.call() if @on_finish

  end

  def publish(message, opts={})

    str.scan(X_EXTRACT) do |part|

      eval_part(*part[1..-1])

    end

    @since ||= :now

    @until ||= :now

  end

  def execute(runner, _backend)

  end

  def parse_time(str)

    str.to_i # FIXPAUL validate

    return :now     if str == "now"

    return :stream  if str == "stream"

    return str.to_i if str =~ /^[0-9]+$/

    raise InvalidQueryError.new("invalid time: #{str}")

  end

end