Create a clone of this sprite.
OptionaloptLayerGroup: stringOptional layer group the clone's drawable should be added to. Defaults to the sprite layer group.
Delete a costume by index.
The deleted costume, or undefined if none existed at that index.
Disconnect a clone from this sprite. The clone is unmodified; in particular its dispose() is not called.
Add a costume at the given index, taking care to avoid duplicate names.