code: function handleMessage(data) {
  
        const message = data;
  
        message.params = that.parser.parse(data);
        message.channel = ch;
        message.ack = ack;
  
        // Ack method for the msg
        function ack() {
          debug('ack delivery', data.fields.deliveryTag);
          ch.ack(data);
        }
  
        if (Array.isArray(message)) {
          that.options.handler(message[0]);
        }
        else {
          that.options.handler(message);
        }
        debug('queue', that.options.queue);
        if (that.options.autoAck) {
          debug('autoAck', 'true');
          ack();
        }
      }
docs: callback which is invoked each time a message matches the configured route.