code: function (host, clientId) {
      // Initializes the object that stores subscriptions
      this.subscriptions = {};
      // Initializes the object that holds the internal client
      this.client = {};
      // Handles the optional clientId parameter
      if (arguments.length === 1 || clientId === undefined) {
          clientId = generateRandomClientId();
      }
      // Connect
      this.client = connectNode(this.subscriptions, host, clientId);
  }
docs: Defines a Simple MQTT client.
  
  @param {string} host - the hostname of the broker.
  @param {string} [clientId]  - the unique name of this client. If no ID is provided a random one is generated