class Redis::SubscribedClient

def subscription(start, stop, channels, block)
  sub = Subscription.new(&block)
  begin
    @client.call_loop([start, *channels]) do |line|
      type, *rest = line
      sub.callbacks[type].call(*rest)
      break if type == stop && rest.last == 0
    end
  ensure
    send(stop)
  end
end