# File lib/amq/client/async/queue.rb, line 275
        def cancel(nowait = false, &block)
          raise "There is no default consumer for this queue. This usually means that you are trying to unsubscribe a queue that never was subscribed for messages in the first place." if @default_consumer.nil?

          @default_consumer.cancel(nowait, &block)

          self
        end