code: function(vid, pid, callback) {
      if (arguments.length === 2) {
        callback = pid;
        pid = null;
      } else if (arguments.length === 1) {
        callback = vid;
        vid = null;
        pid = null;
      }
  
      FTDIDriver.findAll(vid, pid, callback);
    }
docs: Calls the callback with an array of found devices.
  @param  {Number}   vid      The vendor id. [optional]
  @param  {Number}   pid      The product id. [optional]
  @param  {Function} callback The function, that will be called when finished finding.
  `function(err, devices){}` devices is an array of device objects.