code: func QosGlobal(global bool) Option {
  	return func(r *Rabbus) error {
  		r.config.qos.global = global
  		return nil
  	}
  }
docs: // QosGlobal when global is true, these Qos settings apply to all existing and future
  // consumers on all channels on the same connection. When false, the Channel.Qos
  // settings will apply to all existing and future consumers on this channel.
  // RabbitMQ does not implement the global flag.