code: def add(self, album, objects, object_type=None, **kwds):
          
          return self._add_remove("add", album, objects, object_type,
                                  **kwds)
docs: Endpoint: /album/<id>/<type>/add.json
  
          Add objects (eg. Photos) to an album.
          The objects are a list of either IDs or Trovebox objects.
          If Trovebox objects are used, the object type is inferred
          automatically.
          Returns the updated album object.