code: function(interval, callback) {
      if (lookupIntervalId) {
        return;
      }
  
      isRunning = true;
  
      if (!callback && _.isFunction(interval)) {
        callback = interval;
        interval = null;
      }
  
      interval = interval || 500;
  
      globalSerialDeviceLoader.trigger(function(err) {
        var triggering = false;
        lookupIntervalId = setInterval(function() {
          if (triggering) return;
          triggering = true;
          globalSerialDeviceLoader.trigger(function() {
            triggering = false;
          });
        }, interval);
  
        if (err && !err.name) {
          err = new Error(err);
        }
        if (callback) { callback(err); }
      });
    }
docs: Starts to lookup.
  @param  {Number}   interval The interval milliseconds. [optional]
  @param  {Function} callback The function, that will be called when trigger has started. [optional]
  `function(err){}`