code: function connectNode (subscriptions, host, clientId) {
      // Create client
      var url = "tcp://" + host + ":1883";
      var client = mqtt_lib.connect(url, {clientId : clientId});
      // Register incoming message callback
      client.on('message', function(channel, message) {
          // Execute all the appropriate callbacks:
          // the ones specific to this channel with a single parameter (message)
          // the ones associated to a wildcard channel, with two parameters (message and channel)
          var cbs = findCallbacks(subscriptions, channel);
          if (cbs!==undefined) {
              cbs.forEach(function(cb) {
                  if (Object.keys(subscriptions).indexOf(channel)!==-1) {
                      cb(message.toString());
                  } else {
                      cb(message.toString(), channel);
                  }
              });
          }
      });
      return client;
  }
docs: Helper function that connects the MQTT client in node