Asset<D>: An asset is a resource that is loaded asynchronously.loaded: booleanloaded<D>(data: D): Asset<D>data: D | nullerror: Error | nullonLoadEvents: onErrorEvents: onFinishEvents: onLoad(action: (data: D)=>void): thisonError(action: (err: Error)=>void): thisonFinish(action: ()=>void): thisthen(action: (data: D)=>void): Asset<D>catch(action: (err: Error)=>void): Asset<D>finally(action: ()=>void): Asset<D>